The U.S. population is a patchwork of all sorts of immigrants and nationalities, which also translates into wide racial diversity. But the degree of diversity isn’t uniform across the country, which we can see if we examine the “racial dissimilarity index” shown on the map.” Here’s the story. The Census Bureau has data from the 3,241 U.S. counties that divide the population into White and Non-White, with a national average of 78% White and 22% Non-White. They create an index that basically depicts how diverse the racial distribution of the population is within each county: They determine the proportion of each group for each county and adjust each county’s score according to the share of its non-Hispanic White population that would have to move from one census tract in that county to another census tract to achieve uniformity across tracts. (Each census tract typically has a few thousand people.) This score appears to vary widely from county to county, showing that even neighboring counties can have very different racial landscapes. Also keep in mind that two counties could have essentially the same score but be mirror images of racial dissimilarity. Take Allamakee County, Iowa, and Bolivar County, Mississippi, for example. Their dissimilarity scores are very close (66.34 and 58.03), but their populations don’t look the same. The United States really is a patchwork.

How this map was created: The original post referenced an interactive map from our now discontinued GeoFRED site. The revised post provides a replacement map from FRED’s new mapping tool. To create FRED maps, go to the data series page in question and look for the green “VIEW MAP” button at the top right of the graph. See this post for instructions to edit a FRED map. Only series with a green map button can be mapped.

Suggested by Christian Zimmermann.