The most important step is to keep illegal immigrants from having gainful employment, whichever route they took to be here illegally. We must make it possible and mandatory for employers to verify that their new hires are present in the United States legally. After all, it’s the prospect of economic advance, rather than crime or political chaos, that drives almost all illegal immigration. To get control of it — and not just at the border — we have to take away the economic incentive. The knowledge that it will be much more difficult to make money in the U.S. will serve as a humane deterrent against future illegal immigration. Moreover, mandatory verification for new hires will make it harder for existing illegal immigrants to switch jobs, so some of them will leave. In addition, the mandatory implementation of E-Verify would make it easier to prosecute employers who exploit illegal workers and depress wages for lower-income Americans.

The Trump administration has been hesitant to put E-Verify front and center — it’s not as emotive as the president’s signature lines about immigration, and the business wing of the party is opposed. But, as we’ve seen over the last few weeks at the border, once illegal immigrants are in the country, even if they have just arrived, it’s a significant challenge to remove them. E-Verify would serve as a deterrent and diminish the illegal population without the government having to directly remove anyone (although, obviously, deportation is a completely legitimate tool of enforcement).