Single dads are on the rise in the United States, heading a record 8 percent of American households with kids, according to a new analysis by the Pew Research Center.

There were 2.6 million households led by a single father in 2011, a ninefold increase from 1960 when that number was fewer than 300,000, Pew found. This means that men now lead about a quarter of all single-parent families.

The trend underscores the decades-long decline of the two-married-parent model of the American family. Today, about two-thirds of U.S. households with kids are led by a married couple, down from more than nine in 10 in 1960.

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Other demographic shifts also might be contributing to the increasing share of single dads. More and more babies are born to unmarried couples in the United States; four in 10 births in 2008 were to unwed women, according to Pew. What's more, divorce rates are higher than they were in 1960s and 1970s, and changes in the legal system may make it easier for fathers today to gain custody of their kids, Pew researchers noted.

Meanwhile, dads are getting more credit for the influence they have as parents. Breadwinner moms are on the rise across the country, and at the same time, more dads are stepping up as caregivers. Mothers still spend more time, on average, with their children, but fathers have nearly tripled the amount of time they spend with their kids, from 2.5 hours per week in 1965 to 7.3 hours per week in 2011, an earlier Pew report found.

Though their ranks have grown at a faster pace, single dads are still greatly outnumbered by single moms. In 2011, single moms were at the helm of 8.6 million households, up from 1.9 million 50 years ago, according to Pew.

Single dads are more likely to be living with a partner than single moms (41 percent versus 16 percent). And single fathers, on average, are somewhat less educated, older and more likely to be white than single moms, Pew found. They also tend to make more money; 24 percent of single dads live at or below the poverty line, compared with 43 percent of single moms.

Even so, single dads are worse off financially than married fathers. The median annual income for a household of three led by a single dad is about $40,000, compared with $70,000 for a household headed by a married father and $26,000 for a household led by a single mom, according to Pew.

Compared with married dads, single fathers are also usually younger, less educated, and more likely to be non-white. Among fathers under age 30, 27 percent are single parents. Among dads living below the poverty line, more than one-third, or 36 percent, are single, too.

Pew's analysis was based on data from the U.S. Census Bureau. About 52 percent of the men Pew classified as single fathers were separated, divorced, widowed or never married and living without a partner; 41 percent were living with a non-marital partner; and 7 percent were married but not living with their spouse.