This map, made with data from the 1870 census, shows rates of wealth per capita in the settled United States. The scale stretches from white—“under $175 per capita”—to dark orange—“$1300 and over.” (In today’s terms, that range of per capita net worth would be $3,125 to $23,214.29.)
The map was part of a major initiative by Francis Amasa Walker, the young and energetic head of the federal Bureau of Statistics and superintendent of 1870’s ninth U.S. Census. The 1874 atlas that this page comes from was the first attempt to map key statistics of the United States, including distribution of population groups, major geological and meteorological patterns, and the incidences of social ills such as disease and illiteracy.
In her book Mapping the Nation: History and Cartography in Nineteenth-Century America, historian Susan Schulten writes that the maps in Walker’s atlas tried to compare two classes of data visually. Often, Walker juxtaposed another factor with population density.
In this example, the orange shadings designating wealth are overlaid with blue lines that demarcate areas with different population densities. Within the indigo lines, you can pick out the numbers that indicate numbers of people per square mile. The overlay of population density statistics makes it easy to see that most of the wealth was concentrated in urban areas in the North: Chicago; Columbus, Ohio; Pittsburgh; New York; and Boston.
The one outlier is the dark-orange area north of Des Moines, Iowa, where a high per-capita rate of wealth coincided with a population density of only two to 18 people per square mile. I hypothesize that well-established farmers, whose commercial opportunities had been enhanced by new railroad connections to Eastern markets, may have skewed this per-capita rate.
Click on the image below to arrive at a zoomable version, or visit the map's page on the David Rumsey Map Collection's website.
See more of Slate’s maps.