Sunday, June 30, 2019

Name the Country From its Light Pollution

Light pollution in large areas of the world is so bad that if you look at a satellite image of the Earth at night you can name many of the countries around the world just from each country's light pollution. See if you can name the countries shown below from how they appear from space at night.

The countries are not shown to scale.

Can you name this country (above) in Europe? This one is very easy so you get no more clues.

The country above might prove more difficult. So here are two clues

Clues (select text below to reveal)

1. This country is in Africa

2. The light pollution is mostly along the country's large river

This one actually shows two different countries. Can you name both of them?

Clue (select text below to reveal)

On of these two countries begins with the word 'North'. The other country begins with the word 'South'.

The shape of the country above can be a little hard to make out because much of the country is free from light pollution. However you can still make out some major cities and a lot of development around some of the country's coastline.

This country in Asia is much more densely populated and consequently has much more light pollution.

The images for all of the countries shown on this page came from the Light Pollution Map. This interactive map allows you to explore the whole world as it appears at night using VIIRS data. The map allows you to adjust the transparency of the light pollution layer. If you did poorly on this quiz then you can always use this transparency layer to view a map of the world underneath the VIIRS layer.

Let's finish with another easy one. No clues for this one.

Answers (select text to reveal)

1. Italy

2. Egypt

3. North Korea and South Korea

4. Australia

5. Japan

6. Great Britain

Saturday, June 29, 2019

UK Population Change

The Office for National Statistics has released the Population estimates for the UK, England and Wales, Scotland and Northern Ireland: mid-2018. These population estimates show which areas of the UK have seen their populations grow and which have seen a fall in the local population. In mid-2018 the UK population was estimated to be 66,436,000. This represents a 0.6% growth in the national population.

The four local authorities in the UK with the biggest rise in population were all in London (the City of London, Westminster, Camden and Tower Hamlets). 45 local authority areas saw a decrease in population. Many of these were in coastal areas.

Figure 6. in the ONS report is a map of population change in UK local authority areas. This hexbin map shows four different population metrics: the overall population change, the internal migration rate, the international migration rate and the natural change rate. These four map views allow you to see if the population has risen or fallen in each local authority area and whether the change has been driven by internal migration, immigration or natural change.

The ONS report into mid-2018 UK population includes a number of other data visualizations. Some of these provide interesting insights into internal migration in the UK. For example in England there is a general trend of internal migration from urban areas to rural areas. This trend varies across different age groups. Internal migration into cities tends to be highest among young adults. While families with children tend to be the largest group moving from urban to rural areas.

Friday, June 28, 2019

The Geography of College Attainment

In the United States geography and race are two of the main determining factors in adult educational attainment. The Center for American Progress has mapped out the levels of college degree attainment in each of the 3,000+ counties in the United States and Puerto Rico. The map reveals the relatively low levels of college attainment in rural locations compared to more urban areas and the racial attainment gap between the adult white population and the Black, Latinx, and Native populations.

The interactive map Those Left Behind visualizes the Overall Attainment Rates and the Racial Attainment Gaps in each county. If you select a county on the map you can view the county's population, the percentage share of adults with a college degree, the percentage of the white population with a degree and the percentage of Black, Latinx, and Native adults with a degree.

The map includes quick links to four counties which the Center for American Progress has picked out as being indicative of some of the geographical and racial patterns affecting educational attainment. These examples highlight the relatively low levels of the rural population who achieve a college degree, compared to the population in more urban areas of the country. It also highlights some of the urban counties where there is a large racial attainment gap, where the percentage of the white population with a college degree is much higher than the Black, Latinx, and Native populations with a college degree.

Homes at Risk from Rising Seas

An interactive map, created by the Union of Concerned Scientists, allows you to view the number of homes which are at risk from rising sea levels in every congressional district in the contiguous United States. The Property at Risk from Rising Seas, by Congressional District map colors congressional districts by the number of homes at risk from chronic flooding in the coming decades.

The initial map view visualizes the number of homes potentially at risk from chronic flooding in 2045. You can also view the number of homes which will be at risk by 2100. As well as showing homes at risk in 2045 and 2100 you can explore the total current property value at risk, the estimated population effected, and the annual property tax contribution of at risk homes in each congressional district.

The Property at Risk map allows you to explore two different models of climate change. One which will see a moderate rate of sea level rise and one which shows a more extreme rate of rising seas. In the second model the global average sea level is projected to rise about 2 feet by 2045 and about 6.5 feet by 2100.

Climate Central's Surging Seas is one of the best interactive mapped visualizations of the effects of rising sea levels. Surging Seas includes a control which allows you to define the number of feet of sea level rise which you can view on the map. As you increase the amount of sea level rise the areas which will be effected are shaded blue on the map.

The map includes information on the number of people who live in the areas effected for each level of rising sea level. It also allows you to view the total value of property at risk for each level of rising seas.

Thursday, June 27, 2019

Maps Will Tear Us Apart (Again)

Peter Saville's cover for Joy Division's Unknown Pleasure album has become an iconic image. The album cover was inspired by a visualization of the radio waves emitted by a pulsar, which was published in the Cambridge Encyclopaedia of Astronomy. In data science a visualization which is inspired by the graph is often called a 'joyplot' in acknowledgement of the iconic album cover. Although there are probably just as many data scientists who hate the term and refer to these type of visualizations as 'ridgeline plots'.

Over the years a number of maps have used rideline plots, often to signify population density. For example Giorgi Kankia's Population Lines uses ridge-lines to show population density in the country of Georgia. On his map the height of the ridge-lines relate to the number of people living within a square kilometer. The areas shaded red are Russian occupied areas of the country.

James Chesire was perhaps the first person to use a ridgeline plot to map population density (although James himself says this form of map visualization isn't entirely new). His Population Lines map uses ridge-lines to show population along lines of latitude using data from NASA's Sedac. James' population density map has inspired many other population density maps. For example, here is Henrik Lindberg's joyplot map of European population density.

Ridge-lines plots can also be used to visualize elevation. Kenneth Field has published a tutorial on how you can create a ridgeline plot map from a digital elevation model in ArcGIS Pro. His Joy Plots in ArcGIS Pro also includes a brief history of joy-plots. You can enjoy an interactive joy-plot elevation map at San Francisco Terrain.

Joy-plot maps have also been used to visualize Global Temperature Change and the Population of Wisconsin.

The Geography of the European Elections

Earlier this week the Berliner Morgenpost explored the geographical distribution of votes for the Green Party in the 2019 European elections. The maps in Where Germany is Really Green also look at which German municipalities are the greenest, when judged by a number of different environmental criteria.

The newspaper has now taken a closer look at the geographical distribution of the votes for the other 39 political parties who stood in the European elections. In Small parties make the East visible the Berliner Morgenpost has mapped out the areas of Germany where each of the 40 parties received above average support (based on each party's national results). The result is 40 small maps which the newspaper has then organised by geography, to show which parties were most popular in the East, the West, the South and the North of Germany.

21 of the 40 parties were much more popular in the former East Germany. Most of these were some of the smallest parties (in terms of their national vote). The two largest parties the CDU/CSU and the Greens were both especially strong in the west of Germany.

Wednesday, June 26, 2019

The Pacific Ring of Fire

More than 75% of the world's volcanoes and around 90% of earthquakes occur in and around the basin of the Pacific Ocean. This area is commonly called the Ring of Fire. The reason for all this  seismic activity in the Ring of Fire is the presence of converging tectonic plates.

The Ring of Fire can be clearly seen in ResourceWatch's Global Earthquake Hazard Frequency and Distribution map. This interactive map visualizes all earthquake activity around the world, from 1976 to 2002, exceeding 4.5 on the Richter scale. The map shows that there was a lot of seismic activity on both sides of the Pacific Ocean during this period.

The Pacific Ring of Fire can also be clearly seen on John Nelson's Seismic Illumination. This map uses historical earthquake data going back to 1898 to show how earthquake activity can reveal the Earth's tectonic plates. By concentrating on the Pacific Ring of Fire the map is able to show how continental drift causes seismic activity where the Earth's tectonic plates grind beneath each other.

This converging of tectonic plates can also cause volcanoes. National Geographics' How Volcanoes Threaten Millions is a fascinating exploration of the active volcanoes found around the 25,000-mile-long Ring of Fire. The article includes an animated illustration of how tectonic plates collide and create volcanoes.

The article also includes a beautiful exaggerated relief map of the volcanoes and the population centers they threaten in Indonesia. None of these volcanoes are actually in National Geographic's list of the top six life threatening volcanoes on the Ring of Fire. This list maps and names the six volcanoes that National Geographic believe are most likely to threaten humans. For each of these volcanoes the magazine gives its last eruption date and the number of people who live within 60 miles of the volcano.

Will it Rain on Independence Day?

If you have outdoor plans for this year's Fourth of July then you might want to consider the odds of it raining on your parade. Luckily the NOAA has developed a handy interactive map which can actually show you the chance of rain on Independence Day.

Will it Rain on Your Parade uses historical weather records to estimate the odds of rain across the country on the Fourth of July. According to NOAA Hawaii is the most likely location to witness rain. In fact the western slopes have over a 50% chance of rain based on the historical weather records from 1981 to 2010. In the contiguous United States the highest chances of rain are in southern Florida with a 40-50% chance of precipitation. If you wish to avoid the rain you should head to California or Nevada. No location in either of these two states has more than a 10% chance of precipitation.

You may remember the NOAA from such maps as the First Snow Map, an interactive map showing the historic date of the first snow of winter.

How Big is Glastonbury?

The Glastonbury music festival begins today. Two million people pre-registered to buy a ticket for this year's event and, when the tickets did go on sale, the 135,000 tickets sold out in 35 minutes.

135,000 is a lot of people but that number doesn't even come close to the 3.3 million (aggregate) people who attend Donauinselfest in Vienna every year or the 2 million who attend Mawazine in Morocco. The BBC and Statista both agree that Donauinselfest and Mawazine are the two biggest music festivals in the world based on aggregate attendance (although they disagree about which one of the two is actually the largest).

In terms of physical size the Glastonbury site is around 900 acres. If you have difficulty in envisioning how big 900 acres actually is then you can use the Glastonbury Map Overlay to compare an outline of the festival site with any location in the world. If you enter an address into the Glastonbury Map Overlay you can view a polygon of the music festival site overlaid on top of that location.

If you like the Glastonbury map comparison tool then you might also like these other map comparison tools:

Ocean Plastics Pollution - allows you to compare the size of the Great Pacific Garbage Patch with locations across the world
The True Size Of - a map for comparing the size of countries around the globe

Tuesday, June 25, 2019

The State of U.S. Housing 2019

The Harvard Joint Center for Housing Studies has released its 2019 report into the State of the Nation's Housing. It has also released four interactive maps illustrating some of the report's findings.

Among some of the center's key findings on the state of housing in the United States are; rising land prices, large regional differences in housing affordability and the decline of low-rent stock. Despite these pressures on housing the center also found that the share of US households paying more than 30% of their income on housing has declined for the seventh year in a row (in 2017). These four findings can be explored in more detail on the center's interactive maps.

The Burdened by Housing Costs (2017) map shows the percentage of households in each county who pay more than 30% of their income on housing. The map allows you to view the percentage of homeowners and renters burdened by housing costs separately. Comparing these two views reveals that renters are far more affected by relatively high housing costs than homeowners. In fact, although the numbers burdened by housing costs have declined overall, the numbers of renters burdened with housing costs continues to rise.

One reason why the numbers of renters burdened by housing costs are increasing is because the low-rent stock in most metro areas has declined since 2011. You can see how much low-rent stock has declined across the country on the Low-Stock Decline interactive map. This map shows the percentage change in the number of rental units below $800 in different metro areas.

The other two interactive maps, the Rise in Residential Land Prices and the Housing Affordability map show some of the pressures on housing affordability. Both maps show large variations in land prices and housing affordability in different regions. Both land price and housing affordability pressures are incredibly high in California, compared to many other regions of the United States.

The Democratic Candidates on Google Trends

Flourish has mapped out the Top searched Democratic debate candidates on Google during 2019. The Flourish interactive map shows the most searched candidate in each U.S. state from a list of 20 candidates.

It is important to remember that this is a map showing the most searched Democratic debate candidate in each state. Being the most searched candidate doesn't equate to being the most supported. However the map is still interesting in showing where individual candidates are having the most impact.

The map shows that there are some clear geographical patterns in the number of searches for individual candidates. For example Beto O'Rourke is by far the most searched Democrat in his home state of Texas. Similarly Kamala Harris is the most searched candidate in many counties in her home state of California.

Joe Biden and Bernie Sanders appear to be the most searched candidates in the most counties. Let's take a closer look at where more people are searching for Biden and where more people are searching for Sanders.

We can use Google Trends to compare just Joe Biden and Bernie Sanders over the same period (Jan - June 2019). We can then see which of these candidates is the most searched in each metro area. This map shows that Biden is being searched more in parts of the Midwest and the South. Bernie Sanders is searched more in the West and the North East.

Google Trends also allows us to chart the number of searches for each candidate over time. This chart reveals a huge spike for Bernie Sanders in February, when he announced his intention to run in 2020. Joe Biden announced his candidacy in late April and received a similar spike in searches on Google. After that spike his number of searches leveled out at around the same level as Bernie Sanders, although Biden has been searched more in the last few weeks than Sanders.

FiveThirtyEight are tracking how each of the candidates are performing in all the opinion polls. In their average poll of polls on June 19th Joe Biden was on 31.1% support and Bernie Sanders was on 15.7%.

How Green is Your City

Jena is the greenest city in Germany. Berlin ranks as the 21st greenest German city and Munich comes in at number 16 in the list of the country's most green cities.

In the recent elections for the European parliament the Green Party were the second most popular party. The party more than doubled its number of seats by winning twenty-one. The Berliner Morgenpost has been wondering if the areas which voted in the highest numbers for the Green party are also the most green in terms of lifestyle. It has therefore created a number of interactive maps to measure how green each municipality is in a number of different areas.

The maps in Where Germany is Really Green visualize a number of different 'green' categories. These include the percentage of electric cars, the amount of garbage produced, the share of green energy and the percentage of bicycle use. For each of these areas it has created a choropleth map showing the levels in each municipality and the top three green cities judged by the mapped measure.

Using each municipality's results for each measure the Berliner Morgenpost has been able to rank all German municipalities based on their combined scores. Readers can enter the name of their town or city to see where they rank among all German municipalities. As well as discovering a city's overall rank you can also see how they score in each of the different individual areas.

Monday, June 24, 2019

Here's New 3D Vector Mapping Library

HERE, the mapping and location data company, has released a new open source 3D web mapping library called The library is built on WebGL and three.js so it should work particularly well for 3D data visualizations and map animations.

If you want to see some maps created with then check out the examples section of the website. This examples section includes working maps and the source code for those maps. The examples include an animated three.js object dancing on top of an interactive map. The examples also include some more traditional demos, showing how to use different map tile providers and how to create 3D globes with

If you want to start building maps with then you will also want to check out the documentation and tutorial. In the coming months HERE will be releasing new features for These will include the ability to easily add 3D models from HERE, 3D terrain and cinematic effects, such as depth of field.

Search the World

Once upon a time Google Maps had a Wikipedia layer. If you opened this layer on Google Maps you could discover all the places around you which had a Wikipedia entry. The layer was a fantastic way to learn about all the interesting things around your current location. It was definitely one of the most  useful functions on Google Maps. So Google got rid of it.

Luckily there are a few other interactive maps which can help you learn more about the world around you.

Open up Wiki Atlas and you can immediately view all the places around you which have a Wikipedia entry. Click on any of the mapped links and you can read the entry directly from the map. All the locations with a Wikipedia entry are shown with a 3D tower. The height of the tower relates to how often the entry is viewed on Wikipedia. Therefore the height of these towers can provide a rough guide to the relative importance of all the points of interest around your current location.

Wiki Atlas has a handy search function which allows you to filter the results shown on the map by subject. If you want to find and learn more about nearby parks you can just enter 'parks' and the map will only show you nearby entries which refer to parks.

Geopedia is another interesting way to discover information about places in the world. Like Wiki Atlas Geopedia can be used to find and read Wikipedia entries about points of interest around any location. Geopedia uses the Wikipedia API to load all the Wikipedia entries for places around a location on an OpenStreetMap based map. Enter a location into the search bar or right-click on the map and markers will show all the Wikipedia entries near your chosen location.

If you want to discover more about nearby points of interest then you can also use Wikimapia. Wikimapia is one of the most successful interactive maps of all time. For over ten years Wikimapia has provided a great map based resource for discovering information about locations and points of interest around the world.

In essence Wikimapia is a website which lets you describe locations in the same way that Wikipedia allows you to add and edit articles in its wiki database. Like Wikipedia it provides an invaluable resource for researching and discovering information about the world - only with Wikimapia every entry is a real-world location.

To use Wikimapia you just need to search for a location on the map. and click on any of the highlighted areas to discover information about the selected location. For example, if you see an interesting looking building on your daily travels, you just need to click on the building on the Wikimapia map to read its Wikimapia wiki entry.

Inequality in the UK

The UK 2070 Commission is an independent inquiry examining regional inequality in the UK. In order to make recommendations into how the UK economy can be rebalanced the commission has been exploring the economic health of UK cities and regions. Some of these findings can be viewed in two interactive maps.

The Temporal Clusters map classifies urban areas into one of eight different neighbourhood types. These classifications were determined by using census data dating back to 1971. On the map you can view the classifications for each decade since 1971. You can therefore use the map to explore how inequality has changed over the last five decades.

One striking change which is very apparent on the Temporal Clusters map is how the number of families in council rent has dramatically fallen from 1971 to 2011. This is a result of the failure to invest the money raised from selling council homes in the 1980's & 1990's into new public housing stock. The result has been a stark lack of affordable housing in many UK cities and towns.

By mapping the census data for over 50 years the UK2070 Commission are able to determine how neighborhoods have changed economically during the last half of a century. The Neighbourhood Trajectories interactive map colors neighborhoods based on one of  eight categories. On this map it is striking how many inner city areas, especially in the north, are categorized as 'increasing struggling home-owners'. These neighbourhoods are defined as "areas transitioning from families in council rent to a struggling type".

It seems clear to me that the lack of affordable social housing in cities and towns is contributing hugely to the growing inequality of the UK. If you want to more clearly see which areas in the UK have moved from being areas with 'families in council rent' to 'struggling home-owners' filter the Neighbourhood Trajectories map to just show the 'increasing struggling home-owners' layer.

Via: the Carto Blog

Sunday, June 23, 2019

Can You Name These Islands?

Can you name the eight islands in the image above?

I think this Sunday's map challenge is a little difficult so I'm going to tell you which islands are pictured. You just have to guess which is which. The answers are given at the bottom of this post. The islands are (in alphabetical order): Cuba, Great Britain, Greenland, Honshu, Iceland, Ireland, Java and Sri Lanka.

The islands are not to scale!

This map challenge was inspired by Visual Capitalist's much prettier infographic Visualizing 100 of the World's Biggest Islands.

Answers (select text below to reveal)

Great Britain, Greenland, Iceland

Cuba, Java

Sri Lanka, Honshu, Ireland

If you enjoyed this week's map challenge then you might want to see if you can:

Name the City from its Road Network
Guess the Airport from its Map
Name the Country From its Rail Network

Saturday, June 22, 2019

A Literal Map of Capital Cities

I've added translations of capital cities to my literal map of the world. The Planet Dirt interactive map now includes literal translations of country names, U.S. states and many capital cities across the globe.

Planet Dirt is an interactive map of the world on which the place-names have been translated to provide their literal meanings. If you've ever wondered what the name of a country, a state or capital city actually means then you can use this map to find out. The translations of all the capital city names on the map come from Wikipedia's List of National Capital City Name Etymologies. This list doesn't include all capital cities (and not all the cities it does contain are capital cities). Cities, such as London, which have no known etymology are not shown on the map. I've also left off a number of capital cities with names which don't really need translating, such as Washington DC.

Among my personal favorite city names on the map are the surreal sounding 'I've Just Been Cutting Leaves' (Abidjan) and 'End of an Elephant's Trunk' (Khartoum).

Lots of capital cities around the world are named after natural features, such as rivers, mountains, swamps, forests, bays and springs. Just as many cities are named after their defensive features which promise to protect the city's inhabitants from the dangerous world outside. These cities include Vienna (White Fort),  Kuwait City (Fortress by the Sea), Goteborg (Great Stronghold), Tallinn (Danish Castle), Sana'a (Well Fortified) and Rabat (Fortified Place).

Other city names seem to promise their inhabitants a place of peace and rest. These cities include N'Djamena (Place of Rest), Asmara (Live in Peace), Trondheim (A Good Place Called Home), Lisbon (Safe Harbor) and Dar es Salaam (House of Peace).

Cities in the far east often appear to have been named purely for their administrative functions. These cities include Beijing (Northern Capital), Tokyo (Eastern Capital), Kyoto (Capital) and Seoul (Capital).

Friday, June 21, 2019

Is Texas in the South or West?

Yesterday I learned that it can be a big mistake to innocently call Texas a Southern state. Especially when talking to a Texan. In response to my innocent 'error' I received a long account of the history and culture of the Lone Star state. All of which apparently proves that Texas is a Western and not a Southern state. In my defense I hadn't realized that the location of Texas was such a culturally sensitive issue. However it was obviously time to educate myself on geography of the American South.

Wikipedia says that the American South is "located between the Atlantic Ocean and the Western United States, with the Midwestern United States and Northeastern United States to its north". This would be helpful if we had definitive borders for the Midwest, West and Northeast of the USA. Wikipedia also says that the South "is commonly defined as including the states that fought for the Confederate States of America in the American Civil War". This is much more concrete. The South therefore consists of South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, Virginia, Arkansas, Tennessee, North Carolina and Texas, .

If only it was that simple ...

A few years ago Vox asked its readers Which states count as the South and Which states make up the Midwest. They then mapped out the results to show which states their readers considered as part of the South and which states they considered to be in the Midwest. On the Vox maps each state is colored to show how many people said the state was in the South or in the Midwest. The five states which were identified as being in the south by the most people were Mississippi, Alabama, Georgia, South Carolina, and Louisiana (in that order). Of the confederate states Virginia, Florida and Texas got the lowest number of votes for being Southern states. Even so - all three states were still identified as Southern by over 75% of people who replied to the Vox survey.

FiveThirtyEight has also carried out a survey to discover Which States Are in the South (FiveThirtyEight conducted a similar poll asking Which States Are in the Midwest). In the FiveThirtyEight poll Georgia and Alabama were the top two states identified as Southern. Mississippi and Louisiana came in third and fourth. South Carolina, Tennessee, Florida and North Carolina were all considered as Southern by over 60 percent.

In the Vox surveys Oklahoma was considered neither in the Midwest nor in the South. FiveThrityEight readers felt similarly about Missouri, which didn't get many votes for being either in the South or the Midwest. Geographically New Mexico is one of the most southerly U.S. states. However in both the Vox and FiveThirtyEight polls New Mexico was thought to be a southern state by less than 10% of respondents. It is true then that the South seems to be more of a cultural than geographical definition when applied to American states.

From the responses to the Vox and FiveThirtyEight surveys the South is still clearly defined by the American Civil War and the states who belonged to the Confederacy. However of those Confederate states there might just be some indications that both Texas and Florida are beginning to be seen as less Southern than other states in the geographical south (culturally speaking of course). If you search 'Is Texas a Southern state?" (or "Is Florida a Southern State?") you will soon discover that this is a highly contentious question. Most of that contention seems to center around perceived cultural differences between Texans (and Floridians) and the rest of the South.

I'm not sure many Texans would be happy to let the government decide on their status but that's who I'm going to allow the final word. Business Insider has mapped out the four regions and seven subregions which the U.S. Census Bureau uses. The Bureau includes more states than Wikipedia in its definition of the South. It says that Delaware, Maryland, Virginia, West Virginia, Kentucky, North Carolina, South Carolina, Tennessee, Georgia, Florida, Alabama, Mississippi, Arkansas, Louisiana, Texas, and Oklahoma are all in the South. It also includes Washington D.C. in the South.

The Census Bureau divides the South into three subdivisions; the South Atlantic division, East South Central and West South Central. Florida is included in the South Atlantic division. Texas is included in the West South Central division. The Census Bureau definitely doesn't believe that Texas is in the West. However I am prepared to believe that Texas is closer to New Mexico, both culturally and geographically, than it is to Maryland.

Thursday, June 20, 2019

Mapping Ancient Rome

"I curse Tretia Maria and her life and mind and memory and liver and lungs ..."
This curse was found in London, written in Latin upon a lead plate. The curse dates from 43-410 A.D., during the Roman invasion of Britain. The curse is just one of many Roman inscriptions which can be viewed at Roman Inscriptions of Britain.

Roman Inscriptions of Britain records 2,401 monumental Roman inscriptions which were published in R.G. Collingwood's and R.P. Wright's text book of the same name. You can search the Roman inscriptions and their translations in a number of different ways, including by the location where each inscription was found, on the site's interactive map.

The locations of thousands of other historical Latin inscriptions which have been found throughout what was once the Roman Empire can be viewed at EDCS - Map Imperium Romanum. This map uses the Epigraphic Database Clauss-Slaby to show where hundreds of thousands of Latin inscriptions were originally found. The map (shown above) is a pretty accurate map of the extent of the Roman Empire at its peak in around 117 A.D..

If you are interested in Roman history you should also check out, an interactive map that records the locations of archaeological finds, including buildings and artefacts, from the Roman Empire. Using the map it is possible to search for Roman remains near a particular location. As well as showing where archaeological remains have been found the map shows the locations of museums of Roman history and the locations of ancient Roman roads.

If you want help with place-names used in the ancient world then you can refer to the Pleiades website. Pleiades is a great resource for anyone interested in the history and geography of the ancient world. The site is a community based and open-sourced gazette of ancient places. Pleiades has extensive data of place-names used in the Greek and Roman world (it is also expanding into Ancient Near Eastern, Byzantine, Celtic, and Early Medieval geography).

The World's Worst Polluting Cities

We are all contributing to the global heating of planet Earth. However some of us are more culpable than others. If you are a resident of New York, Seoul or Guangzhou then you are among some of the world's worst polluters. A new study has calculated the carbon footprint of 13,000 cities around the globe and found that most of the worst polluting cities in the world can be found in Asia and the United States.

Carbon Footprints of 13 000 Cities has taken a top-down approach to calculating the carbon footprint of towns and cities. The study used data on urban consumption patterns, national carbon emissions, population size and average incomes to estimate the carbon footprint of each city.

The study has been published at the link above but you might find it easier to explore the results as presented by ResourceWatch. ResourceWatch has created an interactive map which presents a 250 meter gridded model of carbon footprints around the world. On this interactive map each 250 meter square is colored to show the estimated Carbon Footprint of that location.

ResourceWatch has also created a graph of the cities with the worst carbon footprints. Seoul, Guangzhou and New York make up the top three worst polluting cities (in that order). Hong Kong (4th) and Los Angeles (5th) have the next highest global footprints. 7 of the top 10 cities are in Asia, the other 3 are all in the Untied States. Moscow has the highest carbon footprint of all European cities. Moscow is only marginally worse than London, which is the second highest polluting city in Europe.

Wednesday, June 19, 2019

The Land of Single-Family Homes

Americans really like detached single-family homes. In European cities apartment living results in more densely populated urban centers than in most U.S. cities. In most U.S. cities land is often zoned to prevent the type of dense residential development that is common in many European cities.The result is that many cities in America are now witnessing an affordable housing crisis.

The New York Times has mapped out the areas of U.S. cities which are zoned for detached single-family housing and the amount of land zoned for other types of housing (for example apartment blocks). In Cities Start to Question an American Ideal: A House With a Yard on Every Lot the NYT claims that many cities and states are now changing their planning regulations to promote the development of non single-family housing.

The multiple small maps in the NYT article use data from UrbanFootprint to show the areas in a number of different cities which are zoned for detached single-family homes. Later in the article the NYT shows these individual cities with larger maps. These larger maps include a percentage total of how much of the city is zoned for detached single-family housing. For example 70% of residential land in Minneapolis is zoned for detached single-family homes.

California is one state which is trying to encourage the development of other more densely packed types of housing. In an attempt to address California's housing supply crisis Senator Scott Wiener has introduced a bill which is designed to encourage the building of apartment buildings in areas with good transit, at the expense of single family homes. If passed the bill will prevent cities and towns from stopping the construction of apartment buildings in certain areas.

Of course not all single-family home owners are happy at the prospect of new tall apartment buildings being constructed in their neighborhoods. The creators of the Stop SB50 Wrecking Homes are definitely opposed to State Senator Scott Wiener's SB-50 bill. The site claims that "SB 50 is an unprecedented law that will destroy thousands of homes & apartments to build luxury housing up to 8 stories high".

This opposition to the bill shouldn't make much difference to their maps as long as they use accurate data. On the Stop SB50 Wrecking Family Homes interactive map three colors are used to show areas where 'Buildings up to 85' feet could be allowed, where 'Buildings up to 75' feet could be built and where 'Buildings up to 75 feet (in jobs rich/good school areas)' will be permitted.

In Peeling the SB 50 Onion UrbanFootprint has also mapped out how SB50 could impact areas in California's largest metropolitan areas. The UrbanFootprint map uses different colors to show zones which are near transit stops, in high quality transit corridors and which are seen as jobs-rich.

In the NYT article San Jose and Los Angeles in California have both been mapped to show how much of these cities' residential zones are currently zoned for detached single-family homes. In San Jose 94% of residential land is zoned for detached single-family homes. In Los Angeles 75% of residential land is zoned only for detached single-family homes. The result is that the West Coast has a huge affordable housing shortage.

The Global Human Footprint

The European Space Agency has released a new interactive map which shows how much of the world has been built upon by the human race. The world's population is now over 7.5 billion. All those people have got to live somewhere - and most of them live in urbanized areas.

ESA's World Settlement Footprint interactive map visualizes human settlements around the world. The map was created from an analysis of satellite imagery collected during 2014-15. The map reveals how much of the world has been urbanized, where urbanization is most dense and which parts of the Earth are still untouched by human settlement.

The Global Rural Urban Mapping Project estimates that around 3% of the world has now been urbanized. Of course the percentage of land which is urbanized varies from country to country. For example 5.9% of the UK is built upon. Even more of the Netherlands has been developed. It is estimated that 14% of the densely populated Netherlands is built upon. On the other side of the Atlantic, in the less densely populated United States, only 3.6% of the land has been developed.

Later this year the World Settlement Footprint map will include an option to view how urban settlements have developed and grown since 1985. The map will use six million satellite images, from 1985 to 2015, to visualize the growth of human settlements on a year-by-year basis around the globe.

Of course if we want to leave most of the world free from human development we will have to learn to live in more densely populated towns and cities. The Pudding has an impressive interactive map which visualizes the world's population in 3D. The Pudding's Human Terrain interactive map shows population density across the globe using 3D population pyramids. The taller a pyramid block on The Pudding map then the more people live there.

The Pudding has also used its own map to explore in more detail the pattern of population density around the world. In Population Mountains The Pudding examines how unevenly the world is populated and how population density can take different forms in different parts of the world.

The Most Famous Czechs Map

The Holy Roman Emperor, King Charles IV, is the most famous person to have been born in the Czech Republic, according to Wikipedia. More people visit the Wikipedia page of Charles IV (Karel IV) than the Wikipedia entry of any other Czech person.

You can find out who is the most famous person from every Czech town on a new interactive map by iROZHLAS. The Most Popular Natives of Czech Towns map reveals the native person with the most Wikipedia visits for 1,749 towns and cities. You can learn more about each of the labeled people by simply hovering over their name on the map. This will reveal a very brief biography and a link to their Wikipedia entry.

iROZHLAS's map was of course inspired by The Pudding's very popular A People Map of the USA, showing the most famous person from each U.S. town and The Pudding's similar map for the UK, A People Map of the UK.

Tuesday, June 18, 2019

The Legacy of Redlining

Under President Franklin D. Roosevelt's New Deal black homeowners were discriminated against through the creation of redlining maps. These maps identified areas with significant black populations and labeled them as too high risk for mortgage support. Black homeowners living in these areas were therefore very unlikely to be successful when trying to refinance home mortgages from the government sponsored Home Owners' Loan Corporation.

Wenfei Xu has released a new interactive mapping tool which allows you to compare the historical redlining maps side-by-side with modern day census data. The Redlining Map tool allows you to explore for yourself if the HOLC redlining maps have had a lasting impact on segregation in your city. Using the modern census data you can view the neighborhoods with a high percentage of black, white or Hispanic people and see if these areas correlate with areas which were deemed at risk or safe for lending purposes in the 1930's.

On the original Home Owners' Loan Corporation redlining maps the areas marked in blue were the neighborhoods deemed desirable for lending purposes. The yellow areas show the neighborhoods which were deemed 'declining' areas. The red areas were the neighborhoods considered the most risky for mortgage support. You can use Wenfei Xu's Redlining Map to see if the areas marked red in the 1930's redlining maps are areas which still have a large black population. You can also see if the blue or 'First Grade' areas are areas which still have a significantly large white population.

The HOLC map from the National Community Reinvestment Coalition also allows you to explore the lasting legacy of the HOLC's redlining maps. This interactive map allows you to compare modern data about income status and the minority population with the HOLC's historical redlining security ratings.

Using the HOLC map you can see if neighborhoods in your city with 'good' HOLC redlining ratings have remained largely white and wealthy or whether your city has become a beacon of social and racial equality. You can also use the National Community Reinvestment Coalition map to see where gentrification has occurred in a city. These are the neighborhoods which received the lowest HOLC redlining ratings but now don't have the stripes from the 'Low to Moderate Income' layer.

Get Your Global Heating Stripes

Last year Ed Hawkins, a climate scientist at the National Centre for Atmospheric Science at the University of Reading, released a powerful data visualization to illustrate how temperatures have risen around the globe over the last century. His warming stripes visualization shows the average yearly temperature for every year over 100+ years.

You can now get your own warming stripes for different regions and countries around the world (and for individual U.S. states). Select a region and then a country from the drop-down menu on #ShowYourStripes and you can view and download an image showing how temperatures have risen over the last 100+ years at your selected location.

Global warming stripes are a very powerful way to visualize a complex issue with one simple and easy to understand image. The general progress from blue to redder stripes is both visually striking and very hard to dispute. The temperature data used for creating the stripes come from the Berkeley Earth temperature dataset and from a number of national meteorological agencies.

Monday, June 17, 2019

America's Most Bike Friendly Cities

Provincetown in Massachusetts is the most bike friendly city in the USA. Alma, Michigan is the second best city for cyclists. Davis, California comes third. You can find out how bike friendly your city is on PeopleforBikes. PeopleforBikes BNA has ranked cities across the United States and Canada based on how easy they are to travel around by bike.

The PeopleforBikes Bike Network Analysis (BNA) ranks towns and cities based on traffic stress, destination access and score aggregation. Traffic stress is calculated by looking at the type of cycling infrastructure available (e.g. the availability of bike lanes, bake paths etc). Destination access is determined by looking at how easy (unstressful) it is to travel across a city by bike. Score aggregation looks at how friendly every census block is for cyclists across the whole city.

PeopleforBikes BNA has created interactive maps for 571 different U.S. and Canadian cities. Each of these individual maps shows the city's overall BNA score. The map also colors all the city's roads to show whether they are high (red) or low (blue) stress for cyclists. The map sidebar includes information on how easy it is to access different services by bike. It also shows how easy it is to access recreational and transportation facilities by bike.

Which Europeans Believe in God?

The Romanians are the most religious people in Europe. 55% of Romanians say that they are 'highly religious'. Estonia is Europe's least religious country. Only 7% of the Estonian population say that they are 'highly religious'. Despite being the most 'highly religious' people in Europe Romanians aren't Europe's biggest believers in God. That privilege belongs to Armenia, where 79% of the people say they believe in a Supreme Being. In comparison only 64% of Romanians believe in God.

According to the Pew Research Center Europeans are generally less religious than people in the rest of the world. However the religious commitment of Europeans varies greatly from country to country. The Pew Research Center has therefore decided to map out the religiosity of European countries.

The interactive map in How Do European Countries Differ in Religious Commitment? shows the percentage of people in each European country who self-identify as 'highly religious'. The Pew Research Center surveyed Europeans on five different questions about their religious belief and practice. The map only shows the results for Europeans' overall religiosity (the percentage of the population who say they are 'highly religious'). However you can view the results from the other four questions about religion in a series of tables. These tables order European countries, from most religious to least, giving the percentage of people who identified as religious in each of the separate questions.

Mapping UK Marine Traffic

Last year Alasdair Rae mapped out the tracks and routes taken by different types of ships around the UK. In Watching the Ships Go By Alasdair created a series of maps to visualize the paths taken by different marine vessels in UK coastal waters. These maps show the different shipping routes taken by cargo ships, passenger ships, fishing boats, high speed craft, military vessels, tankers and recreational craft.

Esri UK has now released a series of similar maps visualizing 2015 marine traffic to reveal the different tracks created by the different types of marine vessel. What Goes on in UK Waters uses AIS data to visualize and explore the different traffic routes taken by commercial, military, fishing, passenger, and recreational boats in UK waters.

The seas around the UK contain some of the world's busiest shipping lanes. The Strait of Dover is just 20.7 miles wide (From England to France) at its narrowest point. Around 600 ships a day pass through this narrow strait. Esri's map of cargo shipping lanes provides a neat visualization of this heavy traffic through the English Channel. While all this commercial shipping traffic passes through the Channel passenger ferries cross these busy shipping lanes traveling between France and England. You can see these passenger ferry lanes on Esri's map of passenger crossings.

Esri's series of maps includes a map showing marine activity during Cowes week (a huge regatta held each year in the Solent). It also includes a map showing recreational marine traffic in the winter and a map showing recreational marine traffic in the summer (people don't seem to take their boats out much during the Winter months).

Sunday, June 16, 2019

Can You Guess the Airport From its Map?

These nine maps show the nine largest airports in the world by passenger numbers. The airports were chosen based on International Airport Reviews Top 20 Airports list.

Can you identify each airport based only on its map? As a very infrequent flyer I would find this challenge impossible myself. I've therefore included the IATA three letter codes for each airport as a clue (I still wouldn't be able to name eight of the airports). Answers are given at the bottom of this post.

While creating these maps I was reminded of the brilliant Trails of Wind interactive map of global airport runway orientations. More runways around the world are built on a north-south orientation than on a east-west axis. You can see this beautifully visualized on the Trails of Wind map. On this interactive map airport runways around the world are colored based on their orientation.

Answers (select text below to reveal)

London Heathrow (LHR), Shanghai Pudong (PVG), Los Angeles (LAX)

Hartsfield-Jackson Atlanta (ATL), Beijing Capital (PEK), Dubai (DXB)

Tokyo Hanenda (HND), O'Hare Chicago (ORD), Hong Kong (HKA)

You might also like to play Name the City from its Road Network and Name the Country From its Rail Network

Saturday, June 15, 2019

Internal Migration in the USA

More people moved out of Los Angeles County than left any other county in the USA between 2015 and 2016. However more people also moved into Los Angeles County than moved into any other county in the country. Esri has mapped out the top twenty counties with the highest outbound and inbound migrations between 2015 and 2016. A lot of counties, like Los Angeles County, appear in the top twenty counties for both outbound and inbound migration. One reason for this is that many of the counties with the highest levels of migration are the most populated counties.

Esri has used data from the IRS to map internal migration in the USA. The Internal Revenue Service records when Americans move address every time they file taxes in a new state. Esri has used this data to map the movements between states and between counties between 2015-2016.

Using the IRS data Esri has created two maps for each state, showing inbound and outbound migration. These maps show which other states people are moving to when they leave a state and which states people are moving from into each U.S. state. Esri has also used the IRS data to show the twenty counties in the country with the biggest outbound migration (and which counties people moved to) and the twenty counties with the biggest inbound migration (and which counties they moved from).

You can view Esri's U.S. internal migration maps either on the Where are Americans Moving Story Map or on the Visualizing Population Migration blog post. Both feature the same maps which use Esri's Distributive Flow Lines tool to create the migration flow visualizations.

You can also view state-to-state migration flows in the United States, from 2009-2013, on the US Migration Flow Map. This map shows that Texas was the most popular destination for Californians moving out of the Golden State during these years. The love that Californians have for Texas was   reciprocated, as California was the most popular destination for Texans moving out of state.

This interactive map by Oregon State University allows you to see which states are the most popular destinations for Americans moving house. The US Migration Flow Map uses flow lines to visualize the numbers of people moving between different states in the USA from 2009-2013. The map includes options to see which states have the biggest exchanges of citizens and to view the most popular state destinations for each individual state.

You can see where people move to and from at the city level in the American Migration interactive map. American Migration visualizes where people moved to and from in America from 2011-2015.

If you hover over a city on the map you can see all the other cities where people moved to, according to the Census Bureau's 2011-2015 American Community Survey. The map uses the Metro to Metro Migration Flows from the survey, which asks respondents if they've moved in the last year where they lived one year ago. As well as the flow-lines on the map, which show all the cities people have moved to, a top 5 list shows the most popular destinations for people moving from the selected city.

Creating Flowmaps

If you are want to create your own flowmaps to visualize movement then you might be interested in Sarah Bellum's Canvas Flowmap Layer, a popular ArcGIS JavaScript API library, which allows you to map objects flowing from one location to another.

The Flowmap-Layer is also now available as a custom map layer for the Leaflet JavaScript mapping library. Like the original ArcGIS flowmap layer Leaflet.Canvas-Flowmap-Layer uses Bezier curves to visualize the movement of objects from one location to another on an interactive map.