Not long ago an academic named Richard Florida made a small ruckus by scientifically proving that the San Francisco Bay Area (along with L.A.) was the best place in the country to be a single woman. He based his finding mostly on data that men here are rich (at least richer, on the mean, than men from any other major metropolitan area) and outnumber single women by about 65,000.
Florida didn't seem to correct for sexual orientation, the favorite straw-man of disgruntled spinsters, but even so the underlying data wasn't really controvertible. It wasn't even new. In 2004 the research firm Teasley published findings that ranked San Francisco as the best place to find a rich, single man in the United States, as measured by San Francisco’s single male "Golden Ratio" of 140%, and specifically accounting for the large percentage of gays (which according to the most reliable figures is considerably less than people tend to believe at about 15%). Similarly a 2004 article in the magazine San Francisco estimated that unmarried straight 20 to 44-year-old men in San Francisco (not including Silicon Valley or Man Jose) outnumbered their female counterparts by about 12,000.
Yet two anecdotal curiosities give us pause: first, an informal study of male opinion and the SF night-life scene describes a ratio that is FAR worse than even the data suggests. Second, and more puzzling, there is widely-shared belief among females that very few eligible/desirable men live in San Francisco.
A study published in in 2007 by two English psychologists (who are better known for a different study that showed the wealthier a man is, the more frequently his partner has orgasms may shed some light. The study looked at marriage patterns in the United States and an interesting trend appeared: unbalanced gender ratios did not seem to problematize proportionally. The research showed that as the sex ratio augmented in favor of women, at first, as you would expect, the women simply turned fussy and went for richer and more powerful men. But at a certain point a curious thing happened: the amount of socioeconomic status a guy needed to get girl increased way more than the math would predict. Specifically when the ratio was tilted in favor of women by 10%, low status men became not 1.1 times less likely to get a girl but 2.3 times less likely and high status men 1.3 times less likely.
In other words, increase the number of males in a system too much and the number of females interested in pairing up GOES DOWN, due to some mysterious psychological trigger. Women won't pick and choose, they won't choose at all. They abandon the enterprise. Romance dies. Society crumbles. Imagine a bar with 100 girls and 100 guys. The bouncer admits 10 more guys and competitively speaking it's as if, for the low status guys, 130 guys walked into the room (and for the high status guys, 30 guys). The bar might as well close for the night. That bar, friends, is San Francisco.