The Center of America's Ten Biggest Cities, 1790–2020

About this chart

Each blue dot is one member of the list at that date, at its fixed location, and the ringed gold dot is their center: the average of the members' latitudes and of their longitudes, each counted as the Method says. The gold line behind it is the path the center has taken, with a small knot at each earlier position; it moves only when members join or leave. The violet diamond and its faint line are the Census Bureau's center of population for the whole country, for comparison. The roster beside the map names the current members in rank order, and the line under the date says which way the center moved and who came in and went out. The map is the lower 48 states on an equal-area projection; it starts on the eastern states and widens when members reach the West. The animation runs the record over thirty-five seconds, holds on the last date for three seconds, and loops. The scrubber under the chart marks each date and pauses on any of them.

Method

The ten are the ten most populous places at each census from 1790 to 2020 as the US Census Bureau ranks them: city limits, not metropolitan areas, from the Bureau's Working Paper 27 (Campbell Gibson, 1998) for 1790 to 1990 and from the 2000, 2010 and 2020 census counts. Each city sits at one fixed point, its entry in the US Geological Survey's Geographic Names Information System (GNIS), usually its downtown; Southwark, a Philadelphia district with no entry, takes the point of Queen Village, the neighborhood at its core. The center is the plain average of the ten cities' latitudes and of their longitudes: each city counts the same, whatever its size. In 1790 Marblehead, Massachusetts, and Southwark tie for tenth with 5,661 people each; both are shown and each counts half, so the average still counts ten. The list keeps the Census Bureau's own changes: Philadelphia's districts rank on their own until the city absorbed them in 1854, and Brooklyn until it joined New York in 1898. The violet diamond is the Census Bureau's center of population for the whole country — the lower 48 states through 1940, all states from 1950. The picture moves from each census to the next; only the 24 censuses carry figures. DataSlapper compiled this series, and every figure on the page is computed from the rows the page serves.

Data sources

• US Census Bureau — Working Paper 27, "Population of the 100 Largest Cities and Other Urban Places in the United States: 1790 to 1990" (Campbell Gibson, 1998)
• US Census Bureau — 2000 and 2010 Census (Summary File 1) and 2020 Census (P.L. 94-171), total population of every place
• US Geological Survey — Geographic Names Information System (GNIS), populated places
• US Census Bureau — National Centers of Population for the 1790–2020 Censuses

Updated 2020

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