LOS ANGELES – Single fathers head a record number of U.S. households with children, the Pew Research Center said in a report released Tuesday. The number of such households has undergone a ninefold increase in 50 years, swelling to more than 2.6 million nationwide.

As of two years ago, single dads led 8 percent of households with kids, compared with just 1 percent in 1960, the Pew analysis of Census Bureau data found. Single fathers now make up nearly one in four single parents.

Pew attributed the increase to many of the same things that ramped up single motherhood, including more children born outside of marriage and higher divorce rates since the 1960s and '70s. Other experts have suggested that divorced and never-married fathers now have more chances to get custody of their children at least some of the time — and more interest in doing so.

"For a long time, men saw parenthood as a package deal," said Stephanie Coontz, director of research and public education at the nonprofit Council on Contemporary Families. "If they didn't have a wife to help them, they tended to not be interested or not feel capable of dealing with the kids."

Today, "we've seen a real decline in the number of dads who walk away from their kids" after divorce, Coontz said.

Some men also have asserted their rights as parents outside of marriage, she added.

Single fathers tend to be younger, poorer and less educated than married ones, the Pew report found. They fare better financially than single mothers, however, even though they are less likely than single mothers to have gone to college.

Among single dads, 41 percent were living with an unmarried partner, Pew found — a slight increase from 1990, when the question was first asked.

The rising number of single dads is another sign that ideas about fatherhood are shifting, something that has repeatedly popped up in family research. Dads are spending more time with their children, Pew has previously found, although they still spend much less time on average than mothers do.