“I understand why students are angry,” said George R. Blumenthal, the chancellor of the University of California, Santa Cruz, where student protests have erupted. “They have to write bigger checks every year, and they can’t get into the classes they want. The reality is they’re paying more and getting less.”

In cutting educational subsidies, states may be penny-wise and pound-foolish, Mr. Ehrenberg said.

Economists have found that higher education benefits communities even more than it benefits the individual receiving the degree. Studies show that an educated populace leads to faster economic growth and a more stable democracy, and benefits the poorest workers the most. The post World War II economic boom, for example, has been attributed to increased college enrollment thanks to the G.I. Bill.

Less-skilled workers have much to gain from enrolling in higher education, given the wage premium that additional training brings. State funding cuts not only reduce the ability for the poor to receive more training, but also disproportionately limit access to the fields that are most important to economic and job growth: sciences, engineering and health care.

These courses are especially expensive to teach partly because of equipment and safety precautions. Because these skills are in such high demand, professors also have more opportunities in the private sector and so can command higher pay.

State laws usually bar colleges from charging different tuition amounts for different undergraduate subjects, regardless of costs. Traditionally the higher cost of technical training has instead been subsidized with state funds.

“When they don’t get the appropriate level of funding, there’s a flight to cheaper programs, like general studies or the humanities,” said Nate Johnson, a higher education consultant and former associate director of institutional research for the University of Florida.

Florida International University graduates more Hispanic engineers each year than any other institution in the 50 states. Since the 2007-8 school year, the state funding the university receives annually per full-time student has fallen by $2,628. The university has been allowed to raise tuition by $1,233 in that time, covering less than half the shortfall.