Aging Professors Create a Faculty Bottleneck

When Mary Beth Norton went to work at Cornell University in 1971, she was the history department's first female hire. But now the accomplished professor has a different mark of distinction: She is the oldest American-history scholar at Cornell.

"I've always thought of myself as the sweet young thing in the department," Ms. Norton, who will turn 69 this month, says with a laugh. "But that's not true anymore."

A growing proportion of the nation's professors are at the same point in their careers as Ms. Norton: ­still working, but with the end of their careers in sight. Their tendency to remain on the job as long as their work is enjoyable—or, during economic downturns, long enough to make sure they have enough money to live on in retirement—has led the professoriate to a crucial juncture.

Amid an aging American work force, the graying of college faculties is particularly notable. According to data from the Bureau of Labor Statistics, the number of professors ages 65 and up has more than doubled between 2000 and 2011. At some institutions, including Cornell, more than one in three tenured or tenure-track professors are now 60 or older. At many others—including Duke and George Mason Universities and the Universities of North Carolina at Chapel Hill, Texas at Austin, and Virginia—at least one in four are 60 or older....