DC is apparently packed with single men and women, according to the Pew Research Center. With a national average of 52% (men) and 48% (women) married, the District sports a mere 28% (men) and 23% (women) married. The next lowest numbers are 47% (men) for Alaska and 43% (women) for Rhode Island. (These numbers are for the 15 and older crowd.)All of these are great points. One other factor that I believe has a large effect is the gender-imbalance in DC. I did some back-of-the-envelope calculations on this last year and figure there are two single men for every single women in DC.
One commentator believes this is due to the unique demographics of DC: very high black population (less likely to marry) and very high Democratic population (more likely to marry later). Another points to the 8.2% gay population as the culprit (along with the marry later point). These are certainly factors, but there's a much more obvious reason that I think carries the bulk of the explanation.
Married people tend to want to start families which generally means a bigger home and unless there's also a big raise, that means moving to the suburbs. In most states, moving to the suburbs can but not always means changing your state. But in DC, it always means leaving DC and heading to Maryland or Virgina (or West Virgina). So the states include both the city proper and the suburbs but DC includes only the city proper. Big difference.
I'm on my way out the door to give a 90-minute presentation on "The Effects of Gender Imbalance on Marriage Markets" at GMU's Osher Lifelong Learning Institute. I'll be discussing examples of DC, India, China, religious groups, and more. There will be around 75 retirees in attendance. Should be fun!