The 1986 immigration law included an amnesty on illegals and sanctions on employers of illegals. But the sanctions have proved toothless, since employers can escape liability by accepting pieces of paper that can easily be forged. The obvious solution is some kind of electronic verification. Visa and MasterCard transfer billions of dollars a day via plastic cards, with high reliability. But government has trouble with information technology: The FBI and the Federal Aviation Administration both had to abandon massive IT programs as unfeasible, despite years of effort and millions of dollars. The answer most likely is subcontracting the verification technology to the private sector.

Capitalism "laughs at frontiers,” wrote the French historian Fernand Braudel. The dynamic American economy has attracted illegal immigrants from Mexico and other Latin American countries to work in construction, hotels and restaurants, meatpacking, gardening and landscaping. We talk as if our immigration laws can structure our labor markets, but in practice, Congress’ task now is to get our immigration laws working in tandem with labor markets. We are not going to expel a population the size of the state of Ohio. But we shouldn’t simply acquiesce to violation of the law. We need to legalize and regularize the flow of immigrants the labor market demands.

And we need to encourage their assimilation into America. Opponents of immigration often express distaste with the growing Latino neighborhoods increasingly visible across the country. One hundred years ago, Henry James expressed similar distaste when he visited the Lower East Side of New York. But in time, those immigrants or their children were assimilated, and today their descendants seem as American as anyone else.

Assimilation then had the wholehearted support of leaders like Theodore Roosevelt; today, many of our elites have transnational (Samuel Huntington’s word) attitudes and regard assimilation as oppressive. The vast majority of ordinary Americans have better sense.

Congress, while rewriting the immigration law, ought to take care to encourage assimilation -- Americanization, as TR put it. For immigration is not just a challenge, it’s an opportunity.