In the April 2010 print edition of The Atlantic, authors Dante Chinni and James Gimpel “analyzed reams of demographic, economic, cultural, and political data to break the nation’s 3,141 counties into 12 statistically distinct ‘types of place.’ When we look at family income over the past 30 years through that prism, the full picture of the income divide becomes clearer—and much starker.” The resulting maps — available online in an interactive version (Flash required) — show how each of “the 12 states” have fared between 1980 and 2010. More from the designers.