Fewer competitive U.S. House districts and safe incumbents after redistricting: In 2010, 70 of 435 U.S. House districts had a competitive partisan balance of 47% to 53%. That was small, but after redistricting in 2011, the number of competitive districts declined to only 53. That number dropped again to 47 seats (only 11% of all seats) after the 2012 election due to shifts in voting behavior. Of 31 vulnerable incumbents (those who won by less than 10% in 2010) affected by redistricting (with a new district drawn with partisanship changing by more than 3%), 26 had their district made safer and only five less safe.
Partisan distortions in politically drawn plans: In 2011, Republican lawmakers drew new district lines in North Carolina and Pennsylvania. In 2012, Democratic U.S. House candidates won more than Republican candidates in both states, but won only 9 of 31 seats.
Partisan distortions in commission drawn plans: In 2011, an independent redistricting commission drew lines in California and a bipartisan commission with a public interest “swing vote” drew lines in New Jersey. In 2013, Republican candidates for the New Jersey assembly won 51% of the vote, but only 32 (40%) of 80 seats. In 2014, Democratic U.S. House candidates won 57% of votes in California’s 53 U.S. House races, but 74% of seats.