National Journal's Richard E. Cohen, who co-authors The Almanac of American Politics, takes a look today at redistricting -- which begins following the 2010 census -- as well as Democrats' House seat pick-ups by region since 2002.

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.

Both parties will give special attention to state legislature elections in 2010 with an eye toward redistricting, as they do at the end of every decade. But as Cohen reminds us: things change, people change.

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.