The immigration reform bill that Sens. Tom Cotton and David Perdue introduced Wednesday — the RAISE Act — won’t become law anytime soon. But it’s a milestone that’s going to change the way we think about immigration, and will be the biggest issue in 2018 and 2020.

There are two simple principles behind the bill. We’re going to admit people on the basis that they’ll make Americans better off. And amnesty is off the table.

The bill would reduce the number of family-preference immigrants, people who come here because they have an immediate relative in the country. Right now two-thirds of our green cards each year go to family members. They’re a source of chain migration, people admitted because they have a relative here, and who once here bring their relatives in.

Under the RAISE Act, the number of family-preference immigrants would drop from 600,000 a year to less than 90,000. Along the way, the bill would eliminate the idiotic lottery system, which at present admits 50,000 people a year who hold a lucky ticket.

The case for family-reunification preferences is far weaker today than in the past. In the 19th century, the immigrants who arrived at Ellis Island didn’t expect they’d be seeing their relatives in the old country again. It was the long goodbye. But today it’s different. Compared to 1965, plane tickets and calling cards are cheap, and Skype is free.

It’s often thought that our existing immigration policies impoverish America, but when economists run the numbers it’s not clear that on net they’re costly. The most respected immigration scholar, George Borjas, concludes that one really can’t say. That’s not the end of it, however.

Even if immigration on net is an economic zero, it still creates winners and losers within the United States and amounts to a wealth transfer from poor to rich Americans. Borjas reports that increasing the immigrant flow by 10 percent depressed the earnings of native-born Americans by 4 percent between 1960 and 2010.

These costs are most heavily felt by African Americans, the most fragile group of citizens, whose unemployment rate is nearly double that of whites, and a 10 percent increase in immigration was associated with a 5.9 percent reduction in the black-employment rate.

In addition, a comparison between current immigrants and native-born Americans misses the opportunity costs of doing better still with higher-quality immigrants. Why not the best?

That’s why the RAISE Act proposes to copy the Canadian points system, which is generally considered the model for immigration reform. Under this system, immigrants can log on to a Web site and see if their work, education and language skills qualify them for admission to Canada.

Right now, a country with little more than a tenth the population of the United States actually admits as many economic migrants a year as we do, people granted entry on the basis that they’ll make native Canadians better off. That explains why Canada can admit so many more immigrants a year than we do, on a per capita basis, without it becoming a political issue. Canadians don’t think their government wants to stick it to them.

We’re going to hear some people object that this is all about politics, that Republicans object to admitting people who are likely to become Democrats when they are naturalized. And there’s gambling in Casablanca.

That’s not a valid objection, however, if the RAISE Act would actually help Americans. If the present regime burdens Americans, we shouldn’t be asked to pay a penalty just to benefit a political party.

In any event, Democrats don’t have standing to complain about politics when they themselves boast that the current law amounts to a political payoff for them. Here’s Democratic speechwriter Dylan Lowe: “Republicans just don’t seem to get it.” With every year that passes, “these demographic changes will create millions of new Democratic voters.”

Second, we’re inevitably going to hear charges of racism. If there’s one thing the Canadian system is not, however, it’s racist. In racial terms, the big difference between the immigration policies of the United States and Canada is that Canada’s give an edge to highly skilled immigrants from Asia while ours favor low-skilled Hispanic immigrants.

The RAISE Act would go a long way toward helping America’s middle class and restoring trust in government. Plus there’s one further collateral benefit: The RAISE Act starkly puts into question the Senate filibuster, since any immigration reform, now and forever in the future, is dead on arrival if Republicans need 60 votes for passage.

F.H. Buckley teaches at Scalia Law School.