Micheal Teitelbaum of CQPolitics reports on a new study by Election Data Services indicating an uptick in population trends favoring southern and western states in congressional reapportionment. As Teitelbaum explains:

Based on its analysis, EDS says Texas would be the big winner among the six states that would gain House seats, with three added to its current 32. If that occurs, Texas — already the nation’s second most-populous state behind only California — would gain multiple House seats for the fourth consecutive decade.
The era of huge population growth for California appears to have peaked, with the EDS projections showing the state holding at 53 House seats. California, which first surpassed long-time population leader New York in the 1970 census, enjoyed a one-seat gain as a result of the 2000 census after taking a huge seven-seat gain in the 1990s. If the projection holds, the 2010 census will be the first that doesn’t produce a House seat gain for California since it achieved statehood in 1850.
The other projected gainers, though, are from among those states that have expanded their congressional rosters in recent years. Arizona, Florida, Georgia, Nevada and Utah would each gain one seat according to EDS’ reapportionment projections.
Of those eight seats that would shift south and west, seven would come from states in the North where thriving industries diminished long before the nation’s economic downturn: Iowa, Massachusetts, Michigan, New Jersey, New York, Ohio and Pennsylvania would each lose one seat.

Teitelbaum notes that the trend seems to have accelerated from last year, when the EDS study projected Texas picking up only 2 seats and Michigan and New Jersey would hold their current delegation numbers.
Teitelbam’s article didn’t say whether the expected gains in the south and west were being driven more by birth rates or migration patterns. But the Election Data Services study notes that a new report by the Pew Research Center, “American Mobility: Who Moves? Who Stays Put? Where’s Home?,” indicated that “only 13% of Americans changed residences between 2006 and 2007, the smallest share since the government began tracking this trend in the late 1940s.”