Americans may be postponing marriage, and fewer are wedding at all. But what about the people who do get married? They're staying together longer than they have in years.

Three in four couples who married after 1990 celebrated a 10-year anniversary, according

to census statistics reported Wednesday. That was a rise of three percentage points compared with couples who married in the early 1980s, when the nation's divorce rate was at its highest.

One reason for the increase, said demographers and sociologists who study families, is that people are marrying later in life, after they have completed their education. Not only are they more mature, but they also are more financially secure.

"People seem to be finding a new marriage bargain that works for 21st-century couples," said Andrew Cherlin, a Johns Hopkins University sociologist who studies families. "It's based on pooling two incomes, replacing the old breadwinner-homemaker bargain that worked well in the '50s."

Researchers increasingly are finding a connection between marriage and education. In 2009, 31 percent of brides had a college degree, up from 21 percent in 1996.

"Marriage has become a much more selective institution in today's society," said W. Bradford Wilcox, director of the National Marriage Project at the University of Virginia. "People who are college-educated, more affluent or more religious are more likely to get married and stay married. People who are not are less likely to get married in the first place, and if they do marry, they're more likely to divorce."