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. 

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.