Something similar has been happening in the market for higher education. Over the last decade, state governments and universities have been chipping away at a pillar of American opportunity: in-state tuition.

Part of this story is familiar to anyone who has watched public universities raise tuition and fees, in some cases by 50 percent or more. But there’s another, less obvious, part of the story. Many of the most elite public universities are steadily restricting the number of students who are allowed to pay in-state tuition in the first place....

Most students attending public universities stay in the state where their parents reside, in large part because in-state students have traditionally received a steep tuition discount. Out-of-state students have long been in the minority and pay tuition closer to that charged by private universities. As recently as 2000, national and regional public universities were similar in this regard. That year, 80 percent of national public university students were in-state, compared with 86 percent at regional public universities.

The pattern at elite national universities was very different. There, the majority of additional students were from other states. Instead of extending their traditional mission of providing an affordable, high-quality education to local residents, national universities focused on recruiting students from other states and nations, many of whom paid much higher tuition rates. As a result, the number of in-state spots relative to the college-going population as a whole declined significantly at national public universities.