Maps

Mapping the Census: A Dot for Every Person

A perfect representation of density.

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Brandon Martin-Anderson

Brandon Martin-Anderson, a graduate student at MIT's Changing Places lab, was tired of seeing maps of U.S. population density cluttered by roads, bridges, county borders and other impediments.

Fortunately for us, he has the technological expertise to transform block data from the 2010 Census into points on a map. One point per person, and nothing else. (Martin-Anderson explains the process in more depth here.)

At times, the result is clean and beautiful to the point of abstraction, but when you know what you're looking at, it's a remarkably legible map. And while it resembles, broadly, Chris Howard's political map of density that appeared after the presidential election, Martin-Anderon's map can be magnified at any point. Users can watch each of the country's metro areas dissolve from black to white. Even stripped of the features (roads, rivers) that shape human settlement, density has its own logic.

The above shot, for example, explains instantly why the Northeast Corridor is Amtrak's most profitable route. That white spot in the middle of the country's densest state is the Pine Barrens, the odd and wonderful land of small towns and cranberry bogs immortalized by John McPhee. The ridges of the Appalachians, curving through Pennsylvania, are as plainly apparent as if the map showed topology instead of population.

By contrast, the towns that run between the great nodes of the Midwest align like strands of Christmas lights, indicating a different type of existence than that of the scrunched territory of the Northeast Corridor.

South Florida, meanwhile, offers a hybrid of the two -- long, dense strips of settlement along the coasts and total emptiness inland.

Because "blocks" are the most finely delineated geographic category of census data, the map isn't a perfectly smooth display, and at the highest magnification there can be suspicious distinctions in density between two sides of a street. But it's still possible to see the fading darkness of a city like Detroit, above, particularly compared with, say, Los Angeles, below.

Explore the full map here.

All images courtesy of Brandon Martin-Anderson.

About the Author

  • Henry Grabar is a freelance writer and a former fellow at CityLab. He lives in New York.