The quantity and character of internal migration in the American past is a contentious
historiographical issue. Over a century ago, Frederick Jackson Turner pointed
to westward migration as a safety valve that profoundly affected the nature of the
Republic. With the closing of the frontier, Turner predicted, the population flow to
the West would decline.1
Turner’s twentieth-century critics argued that the greatest
American population movement was not westward expansion, but rather urbanization,
which accelerated throughout the nineteenth and twentieth centuries. Beginning
in the 1960s, social historians using new quantitative approaches fleshed out the
critique of Turner, arguing that high migration to and between urban areas in the
nineteenth century did not result in improved economic opportunity