The goal of this study is to examine the extent to which population shifts over the post-Great Migration period and divergent trends in segregation across regions contributed to the overall decline in black segregation in the United States in recent decades. Using data from the 1970 to 2000 decennial censuses and the 2005-2009 American Community Survey (ACS), our analysis indicates that black dissimilarity and isolation declined more in the South and West than in the Northeast and Midwest. Nevertheless, regional population shifts account for only a modest amount (8 % to 12 %) of the decline in black-white segregation over the period and for an even smaller proportion of the decline in black-nonblack segregation, in part because the largest declines in segregation occurred in the West while the region with the largest relative increase in the black population was the South. Using more refined census divisions rather than census regions provided some additional explanatory power (shifts across divisions explained 15 %-16 % of the decline in black-white segregation): divisions with larger gains in their share of the black population tended to have larger declines in black segregation. Overall, although the effect of the regional redistribution of the black population on declines in segregation was significant, of even greater importance were other causes of substantial declines in segregation in a wide array of metropolitan areas across the country, and especially in the West, over the past 40 years.