Districts in Iowa tend to be competitive due to strong laws against gerrymandering . By law, the nonpartisan state agency responsible for redistricting must draw districts that are square, rectangular, or hexagonal and match city and county boundaries as much as possible. The agency cannot consider voter registration records and previous election results in the process. In 2012, the state's four congressional seats were split evenly between the two parties, with no candidates winning more than 60 percent of the vote.

1st District and given the 2nd District , 3rd District , and 7th District pieces of the Baltimore area to make them safely Democratic. The 3rd District has been Although Republican U.S. House candidates won about one-third of the vote in Maryland in 2012, they grabbed only one of the eight seats because Democratic state legislators had packed conservative voters into theand given the, andpieces of the Baltimore area to make them safely Democratic. Thehas been described as "a crazy quilt," "a blood spatter from a crime scene," and a "broken-winged pterodactyl, lying prostrate across the center of the state."

3rd District , 9th District and 13th District . An Ohio State University political scientist said Ohio's adopted plan was "the most grotesque partisan gerrymander that I, as a political scientist, had ever seen." Although Obama beat Romney by two points, Republicans took 12 of the state's 16 House seats because the Republican-controlled state legislature had packed Democratic voters into theand

1st District , 2nd District , and 14th District with Democratic voters while drawing other districts to protect Republican candidates. Although Obama won Pennsylvania by 5 points in 2012, Republicans won 13 of the state's 18 U.S. House seats. In what Real Clear Politics called the " Gerrymander of the Decade ," Republican state legislators in Pennsylvania packed the, andwith Democratic voters while drawing other districts to protect Republican candidates. Although Obama won Pennsylvania by 5 points in 2012, Republicans won 13 of the state's 18 U.S. House seats.

1st District , 4th District , and 12th District with Democratic voters. A geographic analysis 12th District is the least compact congressional district in the country. Although Democratic House candidates in North Carolina received a majority of the vote, Republican candidates won nine of the state's 13 House seats because the Republican-controlled state legislature had packed the, andwith Democratic voters. A geographic analysis showed that theis the least compact congressional district in the country.