Thomson Reuters U.S. Democratic presidential candidate Hillary Clinton waves as she sits down to talk during a campaign stop at a small restaurant in Vallejo, California
There are 21 Female CEOs on the 2016 Fortune 500 list. That means that women hold only 4.2% of CEO positions in America's largest companies.
The Fortune 500 annual list ranks the largest corporations in the US by revenue.
Of the 29 companies added to the list this year, just one, Mary Laschinger of paper products and distribution company Veritiv, is a woman.
Mary T. Barra, CEO of General Motors, is the only woman to head a company in the top 10.
There were 24 women in last year's list and 24 in 2014. There are a number of valid reasons that the number has fallen, including retirement, company splits and spin-offs that mean the newly created companies are too small to qualify for Fortune's list.
We've picked out the top nine female CEOs, so scroll through to see who made the list, and meet America's most powerful women bosses.