Among self-employed US workers aged 16+, "in 2012, about one in three self-employed workers was female... About 34 percent of self-employed women in 2012 were age 55 or older, up nearly 13 percentage points since 1993," according to a 2014 analysis of CPS data.
Roche, K. (2014). Female self-employment in the United States: An update to 2012. Monthly Labor Review, (October). Retrieved from www.bls.gov.