The University of Texas had a problem — its undergraduates liked bright-lights, biggish-city Austin so much they didn’t want to leave. Or that’s the optimistic take on it. Many students were simply struggling to finish their degrees. Barely half of each class was graduating in four years.

Most universities are in the same boat. Today just 40 percent of college students earn a degree in four years. This phenomenon is so common that educators now use six years, by which time 59 percent of undergraduates receive their diplomas, as the new normal.

That’s bad news. The extra time slows many students’ progress toward an advanced degree or a good job. When students stay for an additional year, it costs them or their parents as much as $40,000, and at public institutions, taxpayers foot part of the tab. And with undergraduates lingering, there is also less room for other students to enroll. Most important, the longer it takes students to graduate, the more likely they are to drop out.

David Laude, a former senior vice provost in charge of student success at U.T., told me the school’s culture was opposed to four-year graduation rates. But after a Texas-size donnybrook that pitted Gov. Rick Perry, who was fixated on cost-cutting, against the president at the time, William Powers, a deal emerged in 2013. The Texas Board of Regents approved a tuition increase, gave the university $12 million and agreed to invest in programs to help students succeed. The university had already begun drawing up plans to graduate more students on schedule, but Mr. Powers raised the stakes by pledging that 70 percent of the Class of 2017 would graduate in four years.