Americans are less transient than ever, as the percentage of people who moved during the previous year has dropped to historic lows, new census statistics show.

Fewer than 12 percent of people in the United States changed residences between 2010 and 2011, the lowest rate since the census began keeping track in 1948. As recently as 1985, more than 20 percent moved during the year.

The shaky economy and the collapse of the housing market are partly to blame for the most recent drop, but the trend is long-standing. Americans are getting older as baby boomers move into their 60s, and older people don’t move as much as people in their 20s who are finishing school, getting jobs and marrying.

In the most recent census statistics, every socioeconomic group was growing more sedentary, including young adults. Barely 7 percent of people ages 20 to 24 moved in the last year, down significantly from 10 percent who moved between 2005 and 2006.

“These are the people putting their lives on hold,” said William H. Frey, a demographer with the Brookings Institution.

In another reflection of tough economic times, college graduates are moving at the lowest rate since the post-World War II era. Frey attributed that fact to their inability to sell their existing homes as prices continue falling, and a credit crunch limiting their ability to obtain loans and buy new homes.

“College graduates are the fuel of our economy,” he said. “They’re the ones who follow the jobs. To see college graduates stuck in the mud does not bode well for what they can contribute” to the recovery, he said.

The economy has held up better in the Washington region compared with the rest of the country. Census statistics for the District, Maryland and Virginia from 2007, before the recession began, and 2010 show little change.

In each of the years, the three jurisdictions gained roughly 480,000 people. The latest newcomers were slightly more likely to settle in Maryland or the District, while the number of people moving here from another region of the country or abroad dropped by almost 60,000.

Virginia still attracted the most new residents, although less than before. The state got about 20,000 fewer new residents in 2010 than before the recession, and about half of them moved to Virginia from another country.

Overall, about one in five newcomers who moved to the region in the previous year had been living abroad. That includes foreigners coming here to work or study, U.S. service members returning from deployments overseas and American college students coming home after studying abroad.

The census statistics show that most moves are local. About two-thirds of all moves are within the same county, roughly the same as six decades ago. And even people who moved away were apt to move less than 50 miles.

The most commonly cited reasons to move are for housing, family or jobs. Barely 1 percent of the people who were questioned in the last year said they moved because of foreclosure or eviction.

Although Americans’ propensity to move has often seemed like a defining characteristic, the census figures suggest that most people never stray too far from home. Six in 10 people in the United States are still living in the state in which they were born.

But the regional differences are large. More than seven in 10 Midwesterners live in the same state where they were born, compared with less than half of people living in the West.

The District and four states — Nevada, Florida, Arizona and Alaska — have the highest share of outsiders, with less than four in 10 residents who are natives. In some smaller locales, natives are far outnumbered by people who moved there. In Silver Spring, for example, less than 7 percent of the residents were born there.

Staff researcher Ted Mellnik contributed to this report.