Millennials living with parents? It's not just a weak economy.

For the first time since at least 1880, more young adults are living with their parents than with a spouse or significant other.

That stunning shift, reported this week by the Pew Research Center, reflects twin patterns of economic change in America.

It's partly a barometer of the economic challenges facing the Millennials as they navigate launching careers and households in a more difficult economy. But it's also driven by a longer-term story of greater gender equality and the way women’s rising earning power has made them less focused on early marriages.

“This turn of events is fueled primarily by the dramatic drop in the share of young Americans who are choosing to settle down romantically before age 35,” writes Richard Fry in Tuesday’s Pew analysis, which was based on US Census surveys.

The analysis finds that in 2014, 32.1 percent of adults age 18 to 34 were living with their parents. This inched above those who were married or cohabiting (31.6 percent), the heads of single households or with roommates (14 percent), or those in some other living arrangement such as living with another relative or in a dormitory (22 percent).

The share of young people living with parents isn’t actually at record levels. It’s higher than in 1960 but below a 1940-era peak of about 35 percent.

The big change is that the share of age 18-to-34 adults living with a spouse or partner has fallen sharply from a peak of 62 percent around 1960. That reflects later marriages, an overall decline in marriage, and economic shifts. (Some couples who are married or cohabiting can’t afford to live on their own.)

Cultural or social factors are at work alongside the economic ones. 

​For one, as a Monitor cover story on "Singles nation" noted, young Americans nowadays often ​have​ an extended period after college when life revolves as much around a tribe of friends as the search for a soul mate.

The report also notes that about 1 in 4 young people may never marry – a projection based on prior Pew research using 2012 data.  

Although the decline or slowdown in marriage is a broad trend, the patterns for men and women are somewhat different. 

For men, living with parents reflects that they are doing relatively worse in the job market than they used to. Overall, employment among age 18-to-34 men has been falling since it peaked in 1960 at 84 percent. In 2014, only 71 percent had jobs. And adjusted for inflation, their wages also been eroding since 1970 and fell significantly during the 2000 to 2010 period.

For women, the same decades since 1970 have seen rising labor participation, education opportunities, and pay. That has coincided with a decline in early marriage.

"Women have opportunities today and they’re looking for different kinds of relationships and [staying] in school,” says Barbara Schneider, a University of Michigan sociologist.

Even with the general decline in marriage, women age 18 to 34 are still (unlike men) a bit more likely to live with a spouse or partner than with their parents.

Other social trends could be at work, too, such as the rise of single-parent families. "Not only are single-parent families far more common and socially acceptable than they were in the past, but scholars studying low-income or working-class communities have discovered that the women in these communities no longer think it is realistic to depend on the men in their lives," wrote economist Isabel Sawhill in a 2014 New York Times opinion article. "They have seen or experienced too much divorce, infidelity, substance abuse and other bad behavior to trust or fully rely on their partners."

For many Millennials, the delay of marriage or cohabiting means waiting longer to have children, and in that Mr. Fry sees a possible up side: Parents may have increased maturity or financial security to provide a stable home for their children.

Financial security, though, isn’t easy to come by these days. The Great Recession made it harder for many Millennials to forge out on their own. College enrollments spiked, partly as an escape from the flagging labor market. But that added to the weight of college debt.

Even today, the labor market is tight, housing costs in many cities are high, and young people are still racking up student loans.

All this dispels the notion that Millennials are just taking the easy route of moving back home to mommy and daddy, says Professor Schneider. In many cases, it makes sense to stay home longer if parents’ living situations permit.

“They have a breakup with a boyfriend or a girlfriend, or their roommates are really awful or they may get a job in another city and they need to come back to their parents house to get a little bit of time,” she says. “This isn’t a case that they’re running home to be coddled by their mother and their father.”