That’s the question the Pew Research Center raised in a new report released Sunday.

living-arrangements-of-young-adults (image source)

According to the report, in 1968 only 6% of American adults aged 18-31 reported having a roommate who was neither a spouse nor a parent. By 1981 that number was up to 14%. The most recent figures estimate just over a quarter of American Millennials are living with roommates. Most of this change has come at the expense of spouse cohabitation, which is less than half its 1968 rate, down from 56% to 23% in 2012.

But why? Obviously, declining rates of marriage and delayed marriage age have something to do with it. Pew reports that age at first marriage has risen at a steady rate for both genders, with average first marriage age now up by six years since 1968. And, this trend shows no sign of reversal. According to a different Pew report, 4.2 million adults were newlyweds in 2011, compared to 4.5 million in 2008– a trend which Pew’s Senior Research Associate Richard Fry calls “sharp.”

Although the decline in marriage is consistent across education levels, a bachelors degree does further enhance the likelihood that you’ll forgo holy matrimony. College educated adults witnessed a whopping 10% decline in marriage rates over just three years, with 55.3 marriages per eligible thousand in 2011 compared to 61.5 per thousand in 2008.

Other factors? Declining employment and rising college enrollment may both play a role. Again according to Pew, “In March 2012, 39% of 18-to 24-year-olds were enrolled in college, up from 35% in March 2007. Among 18 to 24 year olds, those enrolled in college were much more likely than those not in college to be living at home – 66% versus 50%.”

College enrollment is an interesting case. For the purposes of data collection, Pew considers any college student living in a dorm to be “living at home,” which both inflates the figures for “living at home” and cuts down on potential roommate stats…

The idea of a “best friend” is an old one, but since the mid-sixties friendship and cohabitation have become linked. Perhaps it’s not that roommates are supplanting marriage, but that friendship is increasingly prioritized as an Important Relationship. In a world where American college education is at an all time high, marriage is slow to arrive. But friendship — especially when facilitated by dormitories — comes fast. BFFLs may not get a certificate from the state, but “best friendship” is clearly an institution with real world effects.

By Nerve

Read more on the topic: http://www.theatlantic.com/business/archive/2013/09/how-roommates-replaced-spouses-in-the-20th-century/279210/