The trend is being driven mostly by long-term demographic changes, including higher rates of education and labor force participation dating back to the 1960s women's movement. Today, women are more likely than men to hold bachelor's degrees, and they make up nearly half — 47 percent — of the American workforce.
But recent changes in the economy, too, have played a part. Big job losses in manufacturing and construction, fields that used to provide high pay to a mostly male workforce, have lifted the relative earnings of married women, even among those in mid-level positions such as teachers, nurses or administrators. The jump in working women has been especially prominent among those who are mothers — from 37 percent in 1968 to 65 percent in 2011 — reflecting in part increases for those who went looking for jobs to lift sagging family income after the recent recession.
At the same time, marriage rates have fallen to record lows. Forty percent of births now occur out of wedlock, leading to a rise in single-mother households. Many of these mothers are low-income with low education, and more likely to be black or Hispanic.
In all, 13.7 million U.S. households with children under age 18 now include mothers who are the main breadwinners. Of those, 5.1 million, or 37 percent, are married, while 8.6 million, or 63 percent are single. The income gap between the families is large — $80,000 in median family income for married couples vs. $23,000 for single mothers.
Both groups of breadwinner moms — married and unmarried — have grown sharply.
Among all U.S. households with children, the share of married breadwinner moms has jumped from 4 percent in 1960 to 15 percent in 2011. For single mothers, the share has increased from 7 percent to 25 percent.