The geographic concentration of economic activity across the eastern United States, 1820–2010

• I study the long-run distribution of economic activity over the eastern USA.
• Spatial differentiation of population and manufacturing reached a peak around 1950.
• Agriculture showed initial dispersion followed by increasing concentration.
• The rank-ordering of county manufacturing density is persistent over time.

The historical dynamics of the geographic distribution of economic activity across the eastern United States between 1820 and 2010 are examined using the smallest feasible geographic entities, counties, as units of analysis. The region first experienced increasing spatial concentration of population and manufacturing, with inequality peaking early in the twentieth century. Population and manufacturing have since become more dispersed. Agriculture showed the opposite pattern: initial dispersion followed by increasing concentration. Initially, counties with a high manufacturing density also had a high agricultural density. Eventually, agricultural production moved to outlying areas while manufacturing remained concentrated near where it originated.