From the nytimes.com:

The continuing economic downturn has drastically altered the internal migration habits of Americans, turning the flood of migrants into the Sun Belt and out of states like New York, Massachusetts and California into a relative trickle, an analysis of recent federal data confirms.

Essentially, millions of Americans have become frozen in place, researchers say, unable to sell their homes and unsure they would find jobs elsewhere anyway.

An analysis of new data from the Census Bureau and the Internal Revenue Service by the Carsey Institute at the University of New Hampshire confirms earlier census assessments of a migration slowdown.

The institute’s study compared three years’ worth of data from the Census Bureau’s American Community Survey, which was released early Thursday and covered 2008-10, with the data from 2005-7. Since the survey’s findings are released in three-year increments, this was the first time that researchers had a set of data that included only years since the financial collapse began, allowing them to make a direct comparison to a similar period before the collapse.

Using this and other data from the I.R.S. that many researchers consider even more comprehensive, they found that migration into formerly booming states like Arizona, Florida and Nevada began to slow as soon as the recession hit and continued to shrink even into 2010, when many demographers expected it to level off. At the same time, Massachusetts, New York and California, which had been hemorrhaging people for years, and continued to do so in the three years before the financial collapse, suddenly saw the domestic migration loss shrink by as much as 90 percent.

Mobility always tends to slow in times of economic hardship, and there has been a gradual decline in American mobility for decades. But census numbers released earlier this year showed that domestic migration in 2010 had plummeted substantially since the recession began and reached the lowest level since the government began tracking it in the 1940s.

“When times get really hard it gets really hard for people to up and move,” said Kenneth M. Johnson, the senior demographer at the Carsey Institute, who conducted the analysis. “People who might have left New York for North Carolina are staying put. But that is a very recent change, so that places that had been growing rapidly suddenly aren’t, and the outflow has really slowed down.”

Mr. Johnson said that the same phenomenon could be seen within states, as the growth began to slow in once rapidly growing suburbs, and shrinking cities like Los Angeles and Chicago began to stabilize.

The internal migration data does not include those who came to states from other countries or the natural increase of the population through births. Those changes are major drivers for overall population growth and continued to make the Sun Belt and Western states the biggest population gainers of the decade. And young people, who have long been the most reliable group of new migrants to cities, also appear to be less willing to move to the cities in the Sun Belt.

In an analysis of the American Community Survey data made public on Thursday, William Frey, a senior demographer at the Brookings Institution, found that large metropolitan areas with once-flourishing economies, like Atlanta, Phoenix and Riverside, Calif., are no longer magnets for Americans ages 25 to 34.

“These places that were getting real new interest amid the bubble are not seeing that anymore, and in a way it is making people give another place a second look,” Mr. Frey said. “The dynamics of high housing costs on the coasts and relatively affordable inland is starting to change so, in effect, that shuts off the merry-go-round.”

“If nobody can buy or sell their homes, there’s going to be a stagnancy,” he added.

Mr. Frey said that, in many ways, young people were staying in the more established cities with a kind of wait-and-see approach to the economy. He said he expected the relocation rates to pick up as soon as there were new housing and job opportunities for young adults.

“They are trying to bide their time in a hip place they know,” he said. “But there is going to be a pent-up demand for migration, because right now people are just putting their lives on hold.”