The 2012 results show how Republicans gerrymandered congressional lines to produce favorable outcomes even in states that lean Democratic.
In Michigan, Ohio and Pennsylvania, the clustering of Democrats in metropolitan areas made it easy for Republican line-drawers to pack them into a few districts while giving their own party more modest — yet consistent — advantages in the remaining ones.
In Pennsylvania, where Democratic votes are concentrated in Philadelphia and Pittsburgh, Republicans won 13 of 18 House seats while losing the statewide congressional vote, 2.8 million to 2.7 million. In North Carolina, Republicans drew three districts to be overwhelmingly Democratic and won nine of the other 10, even as House Democratic candidates won the statewide vote, 2.2 million to 2.1 million.
While drawing federal districts to their advantage, Republicans also created favorable state House maps to make it harder for Democrats to wrest control of the redistricting process in 2020. In Michigan, Republican candidates won most of the 110 state House seats despite winning 350,000 fewer votes than Democrats, said Sargeant.
"Clearly, the Republican gerrymander had a lot to do with it," he said.
Politics and redistricting have been intertwined since the nation's earliest days, as shown by the Henry-Madison feud outlined in a 2010 report by the Brennan Center for Justice at New York University School of Law.
The practice of drawing party-friendly districts was given its common nickname — gerrymandering — in 1812. That's when Massachusetts Gov. Elbridge Gerry signed a bill that redrew state senate districts unfavorable to his rivals, the Federalists. The shape of one district was said to resemble a salamander.
One of the most notable partisan battles over redistricting occurred in Texas in 2003, when Tom DeLay, then the U.S. House majority leader, engineered a rare mid-decade remap that so angered Democratic state legislators that most of them fled to Ardmore, Oklahoma, and Albuquerque, New Mexico, to prevent a quorum needed to pass the plan.