The Census Bureau recently released a digital version of the 1940 Census, which allows us to see this awesome county-by-county map of population shifts during the Great Depression. They were, as you can see above, really large.
At the Kauffman Foundation last week, someone mentioned that there's something a bit misleading about descriptions of the current downturn as "the worst since the Great Depression" since the baseline level of prosperity is so much higher. This map helps illustrate the truth in that. One reason people were so mobile during the Depression, after all, is that the level of living standards was really low. When the Depression wracked the Dust Bowl, people weren't just faced with unemployment inadequately cushioned by UI and Medicaid, they were faced with potential starvation. So they picked up and left. Bad as the Depression was, it would have been even worse had people not had the opportunity to do that. And by the same token, our current economic downturn would be less severe if people living in economically weak areas were more willing to drop everything and move to places where the job prospects are better (ironically, generally the exact same places where the outlook was worst during the Depression). But people are less desperate today in absolute terms, and therefore less willing to uproot themselves from their families and friends and communities. That's completely understandable and it reflects the large improvements in material living standards that have occurred over the past seventy years such that even a poor person today has access to things—antibiotics, television, velcro—that basically nobody had back then.
Some people take a "blame the victim" approach to this, arguing that if only today's unemployed Americans showed the grit and determination of their dustbowl forebearers that we'd be okay. I see it the other way around. As technology and living standards improve, macroeconomic policymakers need to raise their game along with everyone else.