From Side Street to Ghetto: Understanding the Rising Levels and Changing Spatial Pattern of Segregation, 1900-1940.

A standard interpretation of the intensification of segregation in the early twentieth century is that residents of Northern cities reacted against a growing African American presence, using segregation as a tool of social control that was less needed in the South. Evidence from newly available data for 134 cities in 1900-1940 puts this interpretation in question in several ways. We find that segregation was already high in 1900 at the neighborhood scale. Not only was it rising, but it was changing its spatial scale as clusters of Black settlement in side streets and alleys disappeared from White districts while expanding into large Black zones. Finally, multivariate analyses show that trends were similar in the North and South, and in neither region was Black population size (i.e., "Black threat") a significant predictor of increasing segregation. The general trends of rising segregation and increasing spatial scale became a nationwide pattern.