That's a startling stat that's hard to appreciate even after pondering maps of U.S. population density like this one: Add metro Dallas-Fort Worth, Houston, Philadelphia, Washington, Miami ...

Traditional population density maps are coloured but flat ... New York City, Philadelphia and Washington DC. The cities are home to a total of 51 million people, making up 15 per cent of the ...

New York City Population ... in population density. Click the button at the bottom of the interactive to select Los Angeles County, for instance, and then click anywhere on the map to generate ...