The percentage of young adults ages 18 to 34 living with parents or parents-in-law has risen sharply since the late 2000s, according to the most recent American Community Survey.
One in three young adults - or more than 24 million - lived in homes of their parents or their parents-in-law in 2012. Washington State checked in just below the national average.
In 1990 and 2000, only one in four young adults lived with parents.
"Young adults aged 25 to 34 traditionally represent about half of all first-time home buyers," noted the National Association of Home Builders. "Their delayed willingness and ability to leave parental homes and strike out on their own undoubtedly contributed to suppressing housing demand further during the Great Recession."
Rising college costs, high unemployment, and unstable incomes are all sending and keeping more young adults home.
States with largest unemployment rates tend to have the most young adults living with their parents, according to the study.