This week, President Trump, in coordination with Republican Senators Tom Cotton of Arkansas and David Perdue of Georgia, signalled his intention to make vast changes to America’s immigration system, cutting back on the number of legal immigrants to the United States by half and shifting to a system that gives preference to people with certain skills.

Various presidents have attempted this approach before, including Lyndon Johnson, who was picking up where John F. Kennedy left off. While Johnson was pushing for a merit-based approach, he was stymied by Southern Democrats acting on racist fears that the country’s demographic profile would change under a merit-based system. The law that passed on Johnson’s watch, the Immigration and Nationality Act of 1965, established an immigration system that prioritizes family reunification and is largely still in place today.

John Skrentny, a sociologist at the University of California San Diego, has researched previous attempts to change immigration policy. I talked to him about various presidents’ efforts to pass merit-based policies, and how those efforts shed light on the White House’s current push. This interview has been edited for length and clarity.

Alana Semuels: What did immigration policy look like before Presidents Kennedy and Johnson proposed these changes?

John Skrentny: In the early 1920s, the United States was coming off of a massive wave of immigration between the 1800s and the 1900s. It slowed down around World War I, but a lot of people were freaking out about it, so they passed these immigration restrictions that were based on the demographic profile of the United States at that time. The point of it was to say, “Take a snapshot, this is what we look like demographically here, let's keep this.” The quotas were allowed based on maintaining these same percentages. It disadvantaged people from southern and eastern Europe, and meanwhile, Asians were almost completely excluded.

Semuels: Why did Kennedy and Johnson want to change this system?

Skrentny: It was a major propaganda issue, in that the Soviet Union was continually hammering against the United States, saying, “Hey, this supposed beacon of freedom doesn’t even want you to come to the United States. Look at how they allocate visas.” We gave very, very few to eastern Europe. Asia had a quota of like 100 for each country. During World War II, the Japanese were telling the Chinese, “Hey, your supposed ally loves you so much they won’t even let you enter their country.”

So then the question was, if we’re going to get rid of the national-origin discrimination, which really gave preference to northern and western Europeans, what should we give preference to? And the view from the Kennedy administration and the view from the Johnson administration was initially skills, which public-opinion polling showed a preference for too.

It’s interesting historically—that idea kind of had synergies or harmonies with what was going on in the civil-rights movement. The civil-rights movement at the time was saying, “Stop paying attention to race—let people go as far as their abilities will take them.” It was kind of a meritocracy approach to immigration.

Semuels: What happened? Why wasn't this enacted?

Skerenty: The problem was that a lot of members of Congress—mostly from the South—were really worried about that approach. They thought that the people with the best skills might be from countries that they didn't think “fit in” best with America. So in order to get votes from Southern Democrats, to support the ending of national-origin discrimination, the White House had to find a different system that satisfied the Democrats. And the system that satisfied them was family reunification. The Democrats’ thinking was that since the U.S. was overwhelmingly white, and mostly northern and western European, that northern and western European potential migrants would have a leg up over everyone else, and that the demographic mix would become self-reinforcing.

Semuels: Did that strategy end up working out the way Southern Democrats wanted it to, or backfiring?

Skrentny: Well, look at the country. You saw a great demand—the number of people wanting these visas—from the parts of the world that the Southern Democrats wanted to exclude, and very little demand from the other places. The Southern Democrats' intransigence really created a situation that allowed people from East Asia especially to use family-reunification preferences. Eastern Europeans, for example, won the right to come to the U.S. on an equal basis with other nations, but they often couldn’t leave their countries without risking their lives. Western Europeans didn’t come because at the time, Europe’s economy was booming. There were plenty of jobs then, and so there wasn't much incentive for Europeans to come all the way to the United States. If there weren’t enough jobs for them in Italy or Greece, they could just go to Germany or the Netherlands to work. Since there wasn’t the demand from Europe, the people using those visas were the people from Latin America and Asia.

Semuels: What else can you say about how the 1965 law led to different outcomes than expected?

Skrentny: Another thing they couldn't have predicted was the development of a knowledge economy, which would create great demand for scientists and engineers. Again, if you're Asian and you come to the U.S. as a scientist or engineer, then you can bring your family members. In American engineering graduate programs, the majority of students are international students.

No one could have predicted America's demographic decline, where people, instead of having three or four kids, now have zero kids, one kid, or two kids. That removes the population of teenagers. Teenagers used to work in warehouses, at Burger King, in agriculture. And now they don’t work for those in the same numbers that they used to. I grew up in Indiana. There was a big thing called detasseling corn, and teenagers would do that. That wasn't in my part of the state, but that was what teenagers did. And now, when there are only one or two kids per family, that labor force is gone. So that's why, when you go into fast-food restaurants, unless you're out in rural areas, you're going to see usually immigrants working there. No one could have predicted that.

Semuels: Was 1965 the only time a skills preference came up in immigration reform?

Skrentny: President Truman and President Eisenhower were supportive of immigration reform. Anyone who did foreign policy, like the White House and the State Department, really didn’t like this national-origin discrimination. It was a constant hindrance to the country’s foreign policy, that the U.S. was trying to be friendly to countries but also saying, “You can’t come here.” This pattern of the White House supporting immigration reform and Congress nixing it, we saw it again with George W. Bush.

Semuels: Americans tend to view their country as a meritocracy, so why are skills preferences seen as such a controversial issue today?

Skrentny: It’s hard to do merit-based reform now because it’s viewed as anti-Mexican, anti-Latin America, anti-anyone who is benefiting from family reunification now. It would cut into what they have. That's politics: If you're losing something, you fight to keep it. Most of the major immigration-reform organizations strongly support the maintenance of family reunification—anything that takes away from that is labeled racist or anti-Latino. The public generally supports a preference for skills, but they’re not heavily invested in it.

The ironies are really interesting: The current defenders of the family-reunification system are exactly the people that the original proposers of it wanted to exclude.