U.S. marriage rates have reached historic lows in recent years. Since 1970 — when about 74 marriages happened annually for every 1,000 unmarried women — the marriage rate declined by nearly 60%, dropping to 31 marriages per 1,000 unmarried women by 2012, the National Center for Family and Marriage Research at Bowling Green State University found.



The descent is even more pronounced for millennials. In 1960, a little over two-thirds (68%) of all 20-somethings were married. In 2008, just 26% were hitched, according to the Pew Research Center.

So what's keeping people from tying the knot?

1. The Recession

The economic shock of the recession put marriage on the back burner for many young adults, according to a 2014 study from the Urban Institute.

The Urban Institute looked at millennials' age-specific marriage rates and projected that, if the post-recession rate continues, the number of millennials who marry by age 40 could drop at least 12% from the rate among current 40-year-olds.

Many millennials don't have the economic freedom or security to pursue marriage because the 2007-2008 recession led to depressed wages and increased unemployment. These young people need to focus on graduating and finding a job, instead of courtship and, eventually, paying for their weddings.

Even if the marriage rate bounces back — notably, college-educated have seen a slight increase since the recovery began — fewer millennials will marry by age 40 than for any previous generation of Americans.

2. The Growing Income Gap

With the income gap growing in America, the poor have gotten poorer. Low-income people consequently value economic stability in a spouse even more than they used to. Paradoxically, there's a shortage of financially stable partners in lower-income communities, which may limit marriages.

"Over the past 130 years, the degree of marriage equality has been directly related to the size of the economic gap between rich and poor,"Andrew Cherlin, a professor of sociology at Johns Hopkins University, told the Russell Sage Foundation.

Incomes, Marriage Rates and Men The Brookings Institute

Incomes, Marriage Rates and Women The Brookings Institute

As shown by the Hamilton Projects' charts, 83% of 30- to 50-year-old men in the top 10% of annual earnings are married today, whereas only 64% of median earners and half of those in the bottom 25th percentile are hitched.

Now, compare that to men in 1970, whose marriage rates were 95% (top earners), 91% (median earners), and 60% (bottom 25th percentile of earners), respectively.

The same arc applies to women of varying income levels, despite a growing spot in the workforce and gradually increasing salaries. The top 10% of female earners was the only group whose marriage rate increased since 1970, while the bottom 70% of earners saw their marriage rates decline more than 15 points.

But the desire to get married doesn't vary with income or education, according to a 2010 Pew survey. About 46% of the college-educated and 44% of those with a high-school diploma would like to get married. Similar percentages of the unmarried who earn just above and below $100,000 a year feel the same.

The less education and money people had, however, the more likely they said they wanted a spouse who could support a family, Pew found. In recent years, our troubled education system and economy have produced fewer bachelors eligible in this respect.

3. Shifting Public Attitudes

Aside from economic factors, people simply feel differently about marriage as an institution today. A notable decline in religiousness could hold the blame for this attitude shift.

When asked, about four in 10 Americans, regardless of age, agreed that "marriage is becoming obsolete," according to a 2010 Pew survey. In a similar poll of voters conducted by Time in 1978, only 28% felt that way. The divorce rate was also at a near all-time high then too.

4. Contraception Use

The rise of contraception made waiting to marry easier for both genders because they could have sex outside of wedlock without worrying as much about getting pregnant, Becky Stevenson and Justin Wolfers write in the Journal of Economic Perspectives.

Since 1985, general contraception, driven by condom use, has increased nearly 20%, according to CDC data. As a technical innovation, birth control especially afforded women the social and economic freedom to forgo marriage and instead pursue an education and career opportunities.

About 50% of those born between 1941 and 1949 married before age 23, Claudia Goldin and Lawrence Katz write in the 2002 Journal of Political Economy. With the FDA's approval of the pill in 1960, though, the age when women married started to rise. For those born after 1949, the percent married before age 23 or 24 plummeted. By the time the 1957 babies reached marrying age, the percent dropped a full 20 points than in 1950.

5. Women In The Workforce

Before 1970, more men than women acted as the breadwinners in marriage. As a consequence of that dynamic, some women may have used commitment as a tool for economic stability. But as women have gained spots in the workforce, they've attained the ability to financially support themselves, which has brought greater social and political freedoms.

In 2012, women composed about half of the labor force, up from 38% in 1970. Their introduction rose steadily from then to about 1990 when it leveled off, according to Pew Social Trends data.

Since women joined the workforce, they've also steadily made more money. In 1963, the median woman in America had no income at all. Since then, inflation-adjusted annual earnings of the median full-time female worker increased to almost $20,000 in 2009.

This trend applies to the long term, but on a smaller scale the relationship between female employment and marriage rates becomes slightly more complex, as The Atlantic's Philip Cohen has pointed out. While little doubt exists that financial freedom decreases women's necessity, and therefore desire, to marry, a major influx in the female workforce stems from married women.

While marriage is declining, it's also changing — women aren't expected to be just housewives anymore.