The New York Times looks at who controlled the redistricting of US congressional seats because of the 2010 census. It then showed an example in North Carolina where Republican control led to the state being less competitive in the past for Democrats. In 2010, Democrats held 7/13 seats in North Carolina. But after the redistricting, in 2012 the Democrats held only 4/13. And all of this is done in a small, compact space. This is a very effective graphic.
Credit for the piece goes to Tom Giratikanon.