SACRAMENTO, Calif. — She wore a brown floral dress for the ceremony. He wore his Army uniform, and after all this time, he still worries that it looked too rumpled to pass muster.

When Flo Swanson married Herm Dorion at Fort Lewis, Wash., in July 1942, the future of the world was uncertain, but they were convinced their future meant building a life together. Seven decades later, it turns out they were right.

“We’ve had a wonderful life,” said Herm Dorion, 94, who like his wife is a musician and retired educator. The couple live at the Atria El Camino Gardens senior community in Carmichael, Calif.

“I wouldn’t have had another person,” said Flo Dorion, 92. “We’ve had ups and downs, but we’ve been in love the whole time.”

While the Dorions have had an extraordinarily long marriage, it’s not unusual these days for older couples to celebrate 40, 50 or 60 years together. But in the future, marriages of similar duration likely will be rare.

These days, wedding bells are not ringing — at least, not as often as they used to. As a result, marriage in America has evolved. But into what?

For the Dorions’ generation, marriage was a bedrock of stability, the foundation of family life. “That was the most unusual generation of the 20th century,” said Andrew Cherlin, a sociology professor at Johns Hopkins University. “They grew up in the Depression and the war. Afterward, the American economy was very strong. People were ready to turn toward home and family.

“The effect of growing up in hard times made them more likely to want a stable family life. That’s one reason we see so many long anniversaries now.”

In contrast, the demographic portrait of marriage today shows the upending of tradition. Only half of American adults are married, a record low, compared with 78 percent in 1950. While the divorce rate has leveled off, the marriage rate continues to drop: In 2010, 6.8 people per 1,000 entered new marriages, census data show, compared with 16.4 per 1,000 in 1946.

And couples today are waiting longer to marry. The national average age of people marrying for the first time is 26.5 for brides and 28.7 for grooms. Researchers suggest the average ages are even higher in urban areas.

Statistically speaking, marriage has become the province of the high-achieving: Two-thirds of adults with college degrees get married, compared with less than half of people with only high school diplomas, the Pew Research Center reported. And people without college degrees are more likely to divorce.

“The people who can get good jobs are marrying and staying together,” Cherlin said. “Those are the college-educated people. Marriage is reflecting the socioeconomic polarization in society.”

Take Julia Spiess and Toby Lewis. She’s 34, a vice president at Perry Communications, and he’s the 39-year-old editor of Valley Community Newspapers. Neither has been married before. Their wedding date is Sept. 22.

“I wanted to wait for the right person,” said Lewis.