This chapter presents new causal evidence on the relationship between black arrivals to cities and white departures, a trend referred to as “white flight.” The simultaneity of black in-migration from the South and white relocation to the suburbs, both of which peaked from 1940 to 1970, suggests that the two population flows may be related. This chapter uses variation in the timing of black in-migration to the seventy largest cities in the North and West to distinguish white flight from other causes of suburbanization. It argues that while white suburbanization was primarily motivated by economic forces, including rising incomes, new highway construction, and the falling cost of credit in the decades after World War II, white departures from the city were also, in part, a reaction to black in-migration.