Trump plays up the threat of terrorism. But the real threat is that our border agencies spend so much time tracking down people who want to be gardeners that they don’t have the resources to track down the people who want to be suicide bombers. Fighting terrorism by going after the whole swath of immigration policy is like fighting germs with a sledgehammer.

There’s a reason Republicans from Reagan to Bush supported reasonably open immigration policies. They are and have always been good for America.

A new summary of the research from the National Academies of Sciences, Engineering and Medicine found that immigrants are integrating into society as well as ever. The bulk of the evidence shows that immigrants have a hugely positive effect on total American G.D.P. while having little effect on overall wages. The surge in Asian immigration will bring a gigantic number of highly skilled people, who end up with higher education levels than the American average, higher productivity levels and higher incomes.