WASHINGTON - Many of the states in the South and West that boasted the country's highest growth rates are experiencing a dramatic slowdown because of the recession, the Census Bureau reported yesterday. The magnet states of Florida and Nevada are seeing more people leave than move in - a reversal from just a year or two ago.

Texas had the biggest population leap, with 478,000 more people living there in the year that ended July 1. Its growth rate of 2 percent last year was marginally lower than that of Wyoming and Utah, which had the top growth rates in the country but are much smaller.

The state population numbers released yesterday reflect how the weak economy and the housing bust have forced many people to stay put. Growth rates were down significantly in several states, including Arizona, Idaho, North Carolina, South Carolina, and Georgia.

Conversely, states such as California, Massachusetts, New Jersey, and New York showed a continued upswing after years in decline in the first half of the decade.

New Jersey's population rose from 8.66 million to 8.71 million in the year ended July 1, a 0.5 percent growth rate. Pennsylvania's rose from 12.57 million to 12.6 million, a 0.3 percent growth rate.

Texas' unemployment rate has stayed at least 1 percentage point below the U.S. average during most of the nationwide recession, which began in December 2007.

Florida and Nevada are the two states that have fallen the hardest and swiftest. In the first five years of the decade, they were routinely among the top five in population gain and growth rate. Just a year ago, Nevada slipped some but still stood at seventh in its growth rate.

But in the latest report, both were among 23 states in which more people moved out than moved in. Florida had a net loss of 31,000, placing it seventh from the bottom. Nevada was 16th from the bottom, with a net loss of about 4,000.

"Florida was a state people moved to," said William H. Frey, a demographer with the Brookings Institution. "Now it's attracting fewer people. It was a growth machine, and it just sort of stopped."

Separately, an independent analysis of the new Census data projected that Texas' congressional delegation would rise by four, to 36 members, for the 2012 elections.

Seven other states, all in the South and West, would gain one new representative, according to the analysis by Polidata L.L.C., a demographic and political research firm based in Corinth, Vt.

Nine states, including New Jersey and Pennsylvania, would each lose one congressional seat under the Polidata projections. Except for Louisiana, the states that would lose seats are all in the Northeast and Midwest, continuing a decades-long trend.

Results of the 2010 Census will be used to reapportion congressional and state legislative districts and to allocate federal funds for many programs.