US: Is More Immigration Always Better?

Over at Vox, Matt Yglesias briefly summarizes the case for more immigration:

Studies done in the United States show that immigration raises average incomes of native-born Americans, including native-born Americans with low skill levels. Immigration is, of course, even better for the incomes of the immigrants themselves, which makes reduced barriers to migration one of the biggest possible game changers for overall global growth. What’s more, as the Economist’s Ryan Avent has recently shown, more immigration could be a highly effective fix to the currently hot topic of secular stagnation.

There are many assumptions packed into this paragraph, and they’re worth examining closely.

First, Yglesias is right to observe that immigration raises the average income of native-born Americans. It’s not clear, however, that immigration raises the average incomes of native-born Americans more than a range of other policy measures, like shifting towards consumption taxation, reforming Social Security and Medicare, or drastically improving the productivity of our education system…