A record 57 million Americans - or 18.1 percent of the U.S. population - lived in multigenerational households in 2012, according to an analysis by the Pew Research Center of the most recent data available measuring multigenerational households.
The rate is up from 17.8 percent in 2011 and has risen dramatically. In 1980, for example, only 12.1 percent of the population lived in multi-generational households.
The trend is mostly being driven by young adults who are living at home, the report revealed.
"After three decades of steady but measured growth, the arrangement of having multiple generations together under one roof spiked during the Great Recession of 2007-2009 and has kept on growing in the post-recession period, albeit at a slower pace," according to Pew's analysis.
Still, the rate is lower than in 1940, when one in four Americans lived in a multigenerational home. But back then, the trend was driven by older people living under the roofs of their children.
For its analysis, Pew defined multigenerational households as having at least two adult generations, such as a parent and an adult child age 25 or older.
Nearly a quarter of young adults - or 23.6 percent - who are between the ages of 25 to 34 lived in a multigenerational home in 2012. That marks more than double the 11 percent in 1980, according to the Pew analysis. The declining employment and wages of young adults is undercutting their ability to live independently. The generation is also marrying at older rates, staying in school longer, and more ethnically diverse.
"Racial and ethnic minorities generally have been more likely to live in multigenerational family arrangements," the Pew report notes. For example, Asian-Americans are the most likely major racial group to live in a multigenerational household at 27 percent, while the rate for non-Hispanic whites was 14 percent in 2012, according to the study.