GOLD-DIGGERS CAN BECOME MORE SELECTIVE. Single women out-earn single men in metro areas.

"They don't need marriage as much," says Stephanie Coontz, who teaches history and family studies at The Evergreen State College in Olympia, Wash. "They're likely to be pickier, and they're likely to delay marriage." Coontz dismisses the notion that successful single women intimidate men and can't find husbands. They just marry later in life, she says.

The opening paragraphs illustrate the importance, in proper social science research, of using attachment to the labor force in any analysis of differences in earnings between men and women.

Women ages 22 to 30 with no husband and no kids earn a median $27,000 a year, 8% more than comparable men in the top 366 metropolitan areas, according to 2008 U.S. Census Bureau data crunched by the New York research firm Reach Advisors and released Wednesday. The women out-earn men in 39 of the 50 biggest cities and match them in another eight. The disparity is greatest in Atlanta, where young, childless single women earn 21% more than male counterparts.

The shift in earnings power started showing up in a few big cities a few years ago and has become widespread. It isn't true for all women in their 20s working full time — overall, they earn 90% of what all men in their 20s make — just for those who don't marry or have kids.

All the same, we'll probably see the 75 cent cookie sale during Rosa Luxemburg Month.