The states that attracted the most people from other states during the period were Texas, North Carolina, Arizona, Georgia and South Carolina.
The population shifts will be felt following the 2010 census, when the nation apportions the 435 seats in the House of Representatives, based on population. Seats in Congress also determine the number of electoral votes states have in presidential elections.
Texas stands to be the biggest winner, picking up as many as four seats, while Ohio could be the big loser, giving up as many as two seats, according to projections by Kim Brace of Election Data Services, a Virginia-based firm that crunches political numbers.
Other states projected to lose single seats are Illinois, Iowa, Louisiana, Massachusetts, Michigan, Minnesota, Missouri, New Jersey, New York and Pennsylvania. Brace projects Arizona to add two seats, while Georgia, Nevada, South Carolina and Utah could add one each. Florida could add one or two seats, Brace said.
Numerous other House seats are in play, depending on whether the nation's economic problems continue to affect population trends. As many as 13 states could gain or lose seats, depending on population trends over the next two years and the accuracy of the 2010 census, Brace said.
California illustrates the importance of an accurate head count. The Census Bureau estimates California has fewer than 37 million people, putting it in danger of losing a House seat. State demographers, however, put the population at more than 38 million, taking the seat out of play.
"If I was somebody in charge of one of the states sitting on the edge, I would be thinking about how I could improve the census in my state, because it does have an impact," Brace said.
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