When Mr. Ulmer, who works for the First National Bank of Alaska, and Tamara Deschaine, 34, were wed three years ago, he wasn’t sure if his marriage would make them better able to save.

But the words of a college economics professor are still fresh in his mind. “He said, ‘The two most important things in a person’s life are their money and their family — in that order,’ ” Mr. Ulmer said. “Twelve years out of college and into the real world, I’ve accepted the truth: He was spot on. Being married gives us the desire to have greater financial security and less debt.”

Ms. Ferguson, who works in Texas for Teva Pharmaceuticals, said, “Maybe I would be more financially secure if I were married.” Although she has a house and a pretty secure retirement in place, she has debts, too. She sees how her married sister has been better able to build up financial assets, even though her sister’s husband was recently laid off. “They have a cushion I don’t have,” Ms. Ferguson said. “I think she’s better off being married. She’s been able to save more and doesn’t have to use all her money just to pay the bills, as I do.”

“If I had someone else,” she said, “it would be easier.”

Jonathan Rauch, another fellow at the Brookings Institution and a leader of the Marriage Opportunity Council, a new multi-institution project, said, “Marriage is thriving among people with four-year college diplomas, but the further down you go on the educational and economic totem pole, the worse it’s doing.”

“There’s a growing danger that marriage, with all its advantages for stability, income and child well-being, will look like a gated community for the baccalaureate class, with ever-shrinking working-class participation,” Mr. Rauch said. “We’re not there yet, but that’s the trajectory we’re on.”

In a nation that places a high value on personal freedom, it could be tempting to wave away these concerns. The decision to go it alone can be every bit as fulfilling and life-affirming as the decision to enter into a marriage. Nevertheless, other data are signaling that for a number of Americans, not marrying carries with it a risk of falling behind economically.