A former student, M. Daniele Paserman, who is now a professor at Boston University, sends me the following email, which I thought was interesting enough to share (with permission, of course):
I bumped into your blog post on the Great Gatsby curve, and I was happy to see you raise the point about the arbitrariness of imposing geographic boundaries in measuring intergenerational mobility (why should one lump Connecticut and Mississippi together?)
Claudia Olivetti and I raise a similar point in our recent paper on the evolution of intergenerational mobility in the US between the end of the 19th and the beginning of the 20th Century. We measure a large increase in the intergenerational elasticity between the the cohort of children born in the 1850s and those born in the 1910s, but almost all of it can be explained by income divergence across regions. In fact, within the Northeast and the Midwest, the intergenerational elasticity was flat, or maybe even falling (it was rising in the South, though).