Where have all the workers gone?

The most recent take from the Bureau of Labor Statistics says the participation rate of all US workers is 63.6 percent of the population — the lowest figure since Dolly Parton sang “9 to 5” in December 1981.

This historically low participation number is directly contributing to the lowering of the unemployment rate, since far fewer people are actively searching for work.

Turns out one of the largest demographic leaving the work force is adult women. The BLS says the rate of female labor participation over the last year has been a statistically significant drop from 58.3 percent in April 2011 to 57.6 percent this April, with 324,000 calling off their job search in March and April, according to the BLS. The rate peaked in April 2000, when it hit 60.3 percent.

In the last 12 months, 1.3 million jobs have been created, with 90 percent of those positions going to men, according to the BLS. Women have gained just 149,000 jobs.

The rate of participation by men 16 and over stands at 69.7 percent, down slightly from the year-ago level of 70.1 percent.

One possible explanation: “There may be some women who are saying, ‘I don’t have to work, I’m not compelled to work in quite the same way that I was during the recession,’” said John Challenger, CEO of Challenger Gray & Christmas, a job-placement agency.

“These are women who picked up the slack for families or couples during the recession to bring in income, but now that the husband has gone back to work, they have more freedom to leave the work force.”

The percentage of working women with high-earning husbands had been on the decline for some time before the recession, according to a soon-to-be-released study by the Federal Reserve Bank of New York.

The study found that the career behaviors of college-educated women correlate directly to their husband’s income.

Between 1993 and 2006, the work force saw an average yearly decline of 0.1 percent in the number of educated married women, a stark contrast with the average growth rate of 2.4 percent each year from 1976 to 1992. And today more young women between 16 and 24 are enrolled in school than in the work force, according to the BLS.

“If you’re a secondary earner and your wage is lower than your spouse, and your spouse’s wage rises, you have less of an incentive to work. This mechanism can explain about one-half to two-thirds of the decline in the growth rate of the participation of educated married women in the data between the mid-1990s up until the 2007 recession,” said Stefania Albanesi, an economist at the Federal Reserve Bank of New York, and one of the study’s authors.

Still, experts are careful not to link the recent drop-off in female labor force participation to any one definitive cause, instead ticking off a host of factors that could be contributing to the current dip, like increased competition from men.

“The recession was dubbed a ‘man-cession’ because so many people who lost jobs were men, working in industries like home construction and manufacturing,” Challenger explained. “As the number of industrial jobs go down, you may see more men entering some of the professions that women have been more predominant in, like health care.”

In addition, as more and more women enroll in college — showing up men in the degree department — many are also postponing jobs.