We can expect this to be another fascinating election campaign with a close outcome. This would be different if the election were decided by popular vote, which the Democrats have won every time since 2008. One important reason for this is the voting behavior of immigrants (defined as persons born abroad), currently 15.6% of the population, and that of their children. Although there are some strong differences between and within certain groups, and increasing numbers of immigrants are voting for the Republicans since Trump has been running for office, the overwhelming majority of immigrants are voting for the Democrats, as they always have.

One reason why the Republicans will likely fail to win the popular vote again this time is the Immigration Act of 1965, which changed immigration in the USA substantially and permanently. The legislation caused a huge shift in both the number of immigrants and the mix of countries from which they were coming. A study that I published recently with colleagues shows that the latter was clearly intentional and corresponded to the wishes of a majority of the population. In contrast, the strong increase in immigration after 1965, particularly from Central and South America and above all through family reunification, was originally neither intended nor wished for by the majority of the population. This example shows how immigration policy can change political majorities in lasting, and partly unexpected, ways.