That’s the main question being asked by Federico Boffa, Amedeo Piolatto, and Giacomo A. M. Ponzetto, all economists. I cruised through the whole paper (pdf) and have some superficial thoughts. One snippet:

Western California is more liberal, even among Republican voters and politicians; Eastern California considerably more conservative […] At a first glance, such a political divide might suggest that a break up of coastal and inland California would be optimal on preference-matching grounds […]

[H]owever [this is a] superficial assessment. [Eastern California] contain[s] a large Hispanic population that overwhelmingly prefers the Democratic party. This group is much less educated, less politically knowledgeable, and less likely to vote than Republican supporters in the region, who are on average older, whiter, and wealthier. At the same time, the left-wing Hispanic working class in the Valley shares the political leanings of highly educated liberals on the coast. This ideological alignment goes beyond mere partisanship and includes shared preferences over policies.

As a consequence, our model suggests that the political integration of California is welfare maximizing. For relatively uneducated inland minorities to have a government corresponding to their preferences, it is essential that they share a state with ideologically aligned liberal elites in the Bay area. Right-wing Californians, instead, are sufficiently educated and influential to have a voice in state-wide politics, despite being in the minority: California had a Republican governor for twenty-one of the past thirty years.

[This lesson] applies more broadly. Disadvantaged ethnic minorities— which are less educated and often politically underrepresented— should belong whenever possible to the same polity as better educated and higher-status voters having similar political preferences. Only then are politicians effectively held accountable to both groups. (29-30)

California is “welfare maximizing”? Somebody help me out here. Isn’t it also possible that poor Hispanics and rich liberals form a voting bloc in California as it is because of how the GOP is patched together? If California split into an East/West, current coalitions would be shattered and it doesn’t follow that rich liberals and poor Hispanics would share the same voting preferences in the new arrangement. It doesn’t follow that rich conservatives and poor Hispanics in a hypothetical East would be at odds, either.

The biggest weakness in the paper, if you can call it that, is that the authors are focused on the fiscal aspects of federalism rather than the diplomatic, cultural, and political aspects. Federalism binds people together and forces them to at least try to come to an agreement about some issues. That’s a big deal, though it’s obviously not sexy.

The paper is focused on the EU and the US. There are lots of interesting insights into the European Union but the US angle is kinda boring (I’m sure is vice-versa for readers living and working in Europe). (h/t Mark Koyama)