Sunday, August 23, 2015

The Maps of the Week



Malfideleco was probably the most talked about map this week. However I think its popularity was more to do with the interest in the Ashley Madison hack rather than the quality of the map. Therefore let's quickly move on to the real maps of the week.

EcoWest has released two interactive maps which allow you to explore 15 years of drought data and 34 years of precipitation data. The Tracking US Drought Severity map visualizes the weekly drought designations from the U.S. Drought Monitor from the beginning of the 20th Century. Select a date from the timeline beneath the map and you can view a heat-map of the drought conditions during that week.

The second map, Rain and Snow in the U.S. Since 1981, shows the total monthly rain and snowfall totals across the country. You can use the timeline beneath the map to choose a date and view a heat-map of precipitation levels for the selected month. This time the timeline includes a graph which shows the total rainfall for each month since 1981.


Websites which allow you to directly compare the sizes of two or more different countries have always been a popular way to use interactive map libraries. OverlayMaps, MAPfrappeMy Life Elsewhere, Mapmerizer and If It Were My Home? are five good examples of apps which allow you to compare one location directly with another on an interactive map.

The True Size of ... is a welcome addition to this growing list of country comparison maps. This map allows you to overlay the outlines of any countries on top of another country on a Google Map. You can type any country or state into the search box to add its shape to the map. You can then drag the shape around the map to compare its size to any other country on the map.

The True Size of ... map makes use of the Google Maps API's geodesic property for draggable polygons. This means that when you drag a country around on the map the polygon shape resizes as you move north or south on the map, compensating in part for the distortions in Google Maps' Web Mercator projection.


There didn't seem to be much interest in my own Shifting Cites map this week. Therefore it is decidedly dodgy that it makes it to this week's Maps of the Week list. I suspect there is some sort of bias involved.

Since the early years of the United States there has been a gradual westward shift in the mean center of population. In 1790 the most populated cities in the U.S. were all on the East Coast. In the 2010 census seven of the ten largest cities were located in the Sun Belt region of the south and west.

Shifting Cities shows the top ten most populated U.S. cities for every decade since 1790. The map also shows the mean center of population in the USA for each decade.
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