Urban Growth in Motion

The City Population Bubble Chart with Proportional Text & Total Population is an animated bubble chart organized into a geographical map that visualizes population changes in cities worldwide from 1950 to 2035. The animation presents the populations of global cities over time, offering an overview of where urban populations are rising and falling.

The map uses data from the 2018 Revision of World Urbanization Prospects report, which outlines key urbanization trends and future projections. Crucially for this visualization, the report tracks population sizes and growth rates of cities worldwide and forecasts how these populations are expected to change up to 2050.

The changing sizes of the circles on the map effectively highlight global trends in urban populations. According to the UN report, many of the fastest-growing urban agglomerations are in Asia and Africa, a trend that becomes especially apparent on the map after 2010. Currently, Tokyo is the world’s largest city, with an agglomeration of 37 million inhabitants. However, the map illustrates how Delhi is projected to become the most populous city around 2028.

A significant limitation of mapping total population rather than population density is the issue of how city borders are defined. The map displays "urban agglomerations with 300,000 inhabitants or more in 2018," which may explain why London is absent—despite its metropolitan population of around 9 million, the City of London itself has only about 9,000 residents. However, my biggest complaint about the map is the lack of interactivity: the timeline cannot be paused or adjusted to select individual years. This restriction makes it impossible to examine the data in any detail.