All in all, I became convinced that high levels of low-skill immigration are good for wealthy Americans and bad for poor Americans. Far more important, high levels of illegal immigration—when you start to get into the millions, as we have—undermines unions and labor standards, lowers wages, heightens social tensions, strains state budgets, widens income inequality, subverts the rule of law, and exacerbates class divides. The effects go far beyond wages, because few undocumented workers earn enough to cover anything close to the cost of government services (such as education for their children) they require, and those services are most important to low-income Americans. In short, it’s an immense blow to America’s working class and poor.

Most labor unions support the current legislation, of course, but few of them seem to acknowledge the possibility of a mass influx of a future illegal workforce. In part, that’s because the SEIU and many other unions have thousands of undocumented members, and raising a fuss about enforcement or opposing the current bill would alienate their own members. It’s probably also that they believe, unrealistically, that the bill would be effective at controlling the border in the future.

And a lot of Democrats have also convinced themselves that even if there’s a wage loss to low-skilled workers, the massive new voting bloc of mostly left-leaning immigrants will ultimately help the little guy. But if millions of new Democratic voters oppose strict immigration control, then there will no Democratic support for meaningful immigration control. And generous social benefits cannot coexist with an open border. (Nor can a more egalitarian society.)