Many of the most important social and cultural changes of the twentieth century—industrialization, the Harlem Renaissance, the advent of jazz, the civil rights movement—would not have played out as they did without the Great Migration. Between 1910 and 1930, at least one million African Americans left mostly rural areas of the South and moved to urban centers in the North. Another six million or more followed in the decades after publication of the Atlas of the Historical Geography of the United States. Finding evidence of the first wave of the Great Migration in the 1932 atlas, one might imagine, would be a simple task.
Finding the Great Migration in these plates, though, is a challenge. The most obvious place to look for this movement would be the maps of the black population, taken from the census. The Atlas of the Historical Geography of the United States juxtaposes maps of the “per cent. of colored population in total population” in 1900 and 1930, but it is difficult to see much evidence of the Great Migration there. These maps emphasize how little things changed at scale of the region, not how much they changed at the level of the city and neighborhood.
The Great Migration is invisible in part because county-level maps often do a poor job of representing large, concentrated populations. Clicking on Philadelphia, New York City, and Chicago will reveal large increases in the black populations of those cities, but the maps at first glance highlight the demographic predominance of African Americans in the South. It is invisible in part because the Great Migration into cities coincided with other large movements of whites, both native- and foreign-born, to the same places. And it is also invisible, perhaps, because the Atlas is doggedly bound up with interpretations of the western frontier. Movements of black southerners to the North did not fit neatly into the geographic interpretation, popular at the time and reflected in many of the Atlas’s maps, that tied the formation of American character, culture, and institutions to westward migration. The Great Migration was novel for its direction, and that novelty left it outside the main currents of the Atlas’s interpretive efforts.
To find the Great Migration in this atlas, we need instead to look in an unlikely place, in a map that condenses thousands of data points from all the county-level population maps into a single view. The “Centers of Population” map records subtle shifts in the distribution of Americans over space, representing the geographic mean of the population as tabulated by the U.S. Census. In this map we see the center of the total population moving uniformly, almost inexorably westward along the 39th parallel into areas once occupied by American Indians (often left uncounted by the census).
Yet when we turn our attention to the centers of African American population, we see a different pattern. From 1880 to 1910, the center of black population is consistently to the southwest, beginning in Northwestern Georgia and ending in Alabama between Chattanooga and Birmingham, along what is today Interstate 59.
This track ends in 1910. The 1920 center of population jumps to the north and east, ending up just on the Georgia side of the Georgia-Alabama state line, not too far from Chattanooga. The demographic change most pivotal for American culture in the first decades of the twentieth century is embedded in one tiny, outlying dot.