The number of American households headed by single fathers has ballooned over the last five decades, according to a new study by the Pew Research Center.Single-father-led households in the U.S. have risen about nine-fold from less than 300,000 in 1960 to over 2.6 million in 2011, Pew says. A record 8% of households with minor children in the U.S. are headed by a single father, up from just over 1% in 1960, according to Pew, which analyzed Census data. Single-mother households have increased four-fold in the same time period.Gretchen Livingston, the study’s author and a senior researcher at Pew, defines “single fathers” as people 15 and older who head their household and report living with their own minor children, including step-children or adopted children. Out of those single fathers surveyed in 2011, 41% were living with a cohabiting partner; 52% were separated, divorced, widowed or never married; and 7% were married but didn’t reside with their spouse. Ms. Livingston was unable to determine whether in some instances the unmarried cohabiting partner was the biological mother of the children in the household.The findings show how rapidly the role of fathers in U.S. households is changing. Fathers are gradually closing the still-wide gap between mothers in terms of time spent with children. A Pew public-opinion survey previously found that providing values and emotional support were considered more important roles for fathers than bringing in income. “We have been doing a lot of research here to look at the changing visions of fatherhood,” said Ms. Livingston. “We’ve seen that a father’s role is going beyond just the breadwinner. Generally, fathers are being expected to fulfill the same type of things as mothers.”The growth in single-father households also comes as single-parent households are generally increasing in the U.S. The number of non-marital births has gone up significantly in recent decades, and divorce rates are higher than they were 50 years ago.Single fatherhood is more common among poorer and less-educated fathers, the study finds. Single dads earn a median income (adjusted to a three-person household) of $40,000, much lower than the $70,000 brought in by married fathers. Only 17% of single fathers hold a college degree, in comparison to 40% of married fathers. And about one-quarter of single fathers live below the poverty line, as compared to 8% of married fathers.Single fathers are financially better-off than single mothers. A single mother brings in $14,000 less than a single father and is much more likely to head a household living below the poverty line — 43% of single mothers do.At the same time, the Pew study finds single fathers are somewhat less educated than single mothers and are more than twice as likely to live with a cohabiting partner. In 2011, 1.1 million single dads were living with an unmarried partner.