Mothers are the primary or sole source of income for a growing number of U.S. families in a dramatic shift in American homes and the workplace since the 1960s, the Pew Research Center said in a study released on Wednesday.
Based on data from the U.S. Census Bureau, the study said a record 40 percent of all U.S. households with children relied on mothers as their main or only source of income. That marked a sharp increase from 11 percent of families in 1960.
The so-called "breadwinner moms" are split into two camps, with married mothers who have a higher income than their husbands accounting for 37 percent and 63 percent consisting of single mothers, the Pew study said.
It said married women who out-earn their husbands tended to be slightly older, disproportionately white and college-educated and much better paid than single mothers, who were younger, more likely to be black or Hispanic and less likely to have a college degree.
Single mothers now make up one-quarter of all U.S. households with children and women make up almost half of the U.S. labor force.
According to the Pew study, the employment rate of married mothers with children has jumped from 37 percent in 1968 to 65 percent in 2011.
In a public opinion survey examining the impact of mothers working for pay, Pew Research found last month that about two-thirds of Americans recognized clear economic benefits for families in the gains moms have made in the workplace.
But the survey found that 74 percent of adults said the increasing number of women working for pay had made it more difficult for parents to raise children, and half said it made it harder for marriages to succeed.
(Reporting by Tom Brown; Editing by Maureen Bavdek and Dan Grebler)