Nearly one-third of American workers make less than $15 an hour, study finds

(CNN) Nearly 52 million workers -- or almost one-third of the nation's labor force -- earn less than $15 an hour, according to a study released Tuesday by Oxfam America, an anti-poverty advocacy group.

These workers, whose annual income is less than $31,200, are disproportionately women and people of color, the study found.

Some 47% of Black workers and 46% of Hispanic workers make less than $15 an hour, compared with 26% of White workers. Some 40% of female workers earn less than that threshold, compared with 25% of male workers.

Half of the women of color in the workforce make less than $15 an hour, as do nearly 58% of single parents.

"It's shameful that at a time when many US companies are boasting record profits, some of the hardest working people in this country -- especially people who keep our economy and society functioning -- are struggling to get by and falling behind," said Kaitlyn Henderson, the study's author and senior research adviser at Oxfam America.