The conclusion of this paper by Anna Maria Mayda, Giovanni Peri and Walter Steingress for the National Bureau of Economic Research is counter-intuitive, but the authors are serious people and the data, as presented, are impressive. The paper’s title is “The Political Impact of Immigration: Evidence From the United States.”
Here are the key findings:
Our strongest and most significant finding is that an increase in high-skilled immigrants as a share of the local population is associated with a strong and significant decrease in the vote share for the Republican Party. To the contrary, an increase in the low-skilled immigrant share of the population is associated with a strong and significant increase in Republican votes. These effects are common to presidential, House and Senate elections. Combining the two effects, the net impact of the increased immigrant share on the average U.S. county was negative for the Republican Party between 1990 and 2010. This was because immigration in this period was on average college-biased.
Anecdotal evidence suggests, and we confirm in our data, that on average immigration in U.S. counties reduces the Republican vote share. Political scientists and analysts seem to read this evidence as driven by a “pro-Democratic Party” direct political effect – i.e. the idea that naturalized immigrants vote predominantly for the Democratic party, which has a pro-immigrant platform – and by the fact that this effect dominates whatever indirect effect immigration has on the way existing voters vote. At first sight, this interpretation may seem consistent with the empirical evidence: an increase in the share of citizen (voting) migrants reduces the Republican vote share, while an increase in the share of non-citizen migrants has no effect on average (see Mayda et al. (2016)). However, a closer look suggests that the main impact of immigration on voting outcomes comes from the skill level of immigrants – which affects the voting behavior of existing voters – and not from whether or how naturalized immigrants vote.
The authors point out that the effect of immigration in Europe is the opposite–it boosts conservative parties–and attribute this to the fact that European immigration is, on average, lower-skilled.
This finding is, as I said, counter-intuitive, but the paper clearly lays out its methodology. So, have at it!