Since the 2002 results of new redistricting lines in most states, House Republicans have lost 52 seats. Losses are spread across the nation, though they come disproportionately in the Northeast, where Republicans are down 20 seats. They lost 15 in the Midwest, 11 in the West, and six in the South.

In nine states, Democrats have picked up at least three seats since 2003. Leading the pack are New York (7-seat gain) and Pennsylvania (5-seat gain). Democrats have gained three seats in each of these states: Arizona, Colorado, Connecticut, Florida, Illinois, Ohio and Virginia. Arizona, Colorado and Connecticut are especially notable because each has a House delegation of eight seats or fewer.

Democrats have lost seats in two states since 2003. Their biggest setback (5-seat loss) has been in Texas, chiefly as a result of the controversial 2004 redistricting spearheaded by then-House Majority Leader Tom DeLay. They are down one in Louisiana, pending the outcome of that state's Dec. 6 runoffs.

With another round of redistricting scheduled to start in 2011 following the 2010 census, both parties have begun intensive review of possible new lines plus the broader reapportionment that will shift seats from some states to others because of population changes. The election results since 2002 offer a reminder that House district lines that initially seemed favorable to one party can become less predictable in the midst of broader political changes or the appeal of individual candidates.

These changes are based on the agreed results in 430 districts plus the tentative assumption that the current leader in three other districts will be the eventual winner; the listings do not include two Louisiana districts -- currently split between the two parties --where a Dec. 6 runoff is scheduled. With those results, the House would have 256 Democrats and 177 Republicans, with two undecided. In 2003, the House had 205 Democrats and 229 Republicans, with one Independent.