By Susan Heavey
WASHINGTON (Reuters) - The iconic picture of the traditional American household has faded over the last four decades as the number of married couples with children has seen a steep decline and more people are living alone, according to U.S. Census Bureau data.
Since 1970, the portion of U.S. households that include families with two married parents and children fell by half, from 40 percent to 20 percent last year, according to the U.S. Census Bureau.
"That's at a historic low," Jonathan Vespa, one of the report's co-authors and a researcher in the Census Bureau's Fertility and Family Statistics Branch, told Reuters on Tuesday.
Meanwhile, the number of single-person households grew from 17 percent in 1970 to nearly 28 percent in 2012, according to the Census' report.
The findings, based on Census' annual American Community Survey from 2011 and 2012, underscore the shifting notion of family in the United States as more people opt for other types of living arrangements and highlight the nation's declining birth rate.
"Over the last half-century, the trend in the U.S. has been toward smaller households, fewer family and married-couple households with children, and more people living alone," Vespa said in a statement.
"If people are waiting until later to get married and waiting to get children and they're not living with their parents, then they're probably living alone," Vespa told Reuters.
While married couples with children were the majority decades ago, now nearly 57 percent of U.S. households are childless. In 2012, about 29 percent included childless married couples and nearly 28 percent included people living alone.
Despite the decline in married parents with children, that is still the norm for most U.S. children, researchers said. "For all of the change that's going on, we still do see the majority of children are living with married parents," Vespa said.
Among families that do have children, parents and children still struggle to cope with economic strain, especially in the wake of the 2007-2009 recession.
For example, the number of households with young children that included at least one parent who was unemployed rose by a third between 2005 and 2011, from 2.4 million to 3.2 million, the Census found. States such Nevada, Hawaii and Florida saw an even higher rate of increase.
"During the recession, economic well-being worsened for families with children," said Jamie Lewis, another Census demographer and co-author of the report.
"Home ownership among families declined, while food stamp receipt and parental unemployment increased. Even after the recession officially ended in 2009, these measures remained worse than before it began," Lewis said in a statement.
Families in Michigan, Arizona, California and Ohio saw the biggest decline in home ownership, according to Census' data.
Overall, homeownership among households with children fell 15 percent between 2005 and 2011 to 20.8 million, Census said.
Other findings included:
* The number of people per U.S. household fell from 3.1 to 2.6 on average between 1970 and 2012.
* In 2012, 66 percent of households consisted of two or more people related by birth, marriage or adoption living together, compared with 81 percent in 1970.
* In 2011, there were 605,000 same-sex couple households in the United States, including both married and unmarried couples. Same-sex couples also had the highest share of unions in which both partners had a bachelor's degree.
* Four percent of those in married heterosexual couples were of different races compared to 9 percent of unmarried heterosexual partners and 12 percent of same-sex couples.
(Reporting by Susan Heavey; Editing by Cynthia Johnston and Leslie Gevirtz)