But that edge doesn't translate to Washington, which is among a handful of states that redraws its congressional districts using a bipartisan commission.
So far, it appears that the task of dividing Washington into Democrat, Republican and competitive districts is working out for most people.
"We're a bit of anomaly," said Todd Donovan, a Western Washington University political scientist. The Washington redistricting process is "probably one of the most clean in the country. It has a track record of producing competitive state legislative districts and competitive congressional districts."
Nationally, gerrymandered districts in 2012 helped Republicans hold onto a 33-seat majority in the House. Nationwide, Democratic candidates for the House received 1.4 million more votes than their GOP opponents, yet Democrats remained in the minority. It was only the second time since World War II that the party receiving the most votes had failed to win a majority of House seats, according to statistics compiled by the House clerk.
Before the 2010 election, the GOP had majorities in 36 state legislative bodies. Afterward, the party controlled 56. In half the states, Republicans won control of the entire redistricting process. In other states, Republicans gained control of at least one legislative chamber, limiting the ability of Democrats to draw districts that favored their candidates.
In all, Republicans controlled the process of drawing the boundaries for 210 House districts, compared to just 44 House districts for the Democrats. The rest were drawn by split legislatures or, in a few states, independent commissions that are supposed to be nonpartisan.
The other states that have independent commissions are California, Arizona, Hawaii, New Jersey and Idaho.
After decades of initiatives by the League of Women voters and court fights challenging legislative-drawn districts, Washington lawmakers created the commission in 1982. A year later, the Washington state Redistricting Commission was made permanent into the state constitution following voter approval. The commission is made up of four representatives picked by the two parties and a non-voting chair.
Following population growth in the 2010 Census, Washington gained one congressional seat for a total of 10. The commission went to work the next year, drafting different maps and traveling the state to hear public testimony. They approved the new map with only two hours to spare before their mandatory deadline. Had they failed to agree on a map, the task of redrawing the political map would have gone to the state Supreme Court.
Currently, Democrats hold six of the 10 congressional seats.
The commission drew a map that concentrated most Democrat-leaning districts along the urban and suburban Puget Sound corridor and the Olympic Peninsula. Two large Republican districts cover most of Eastern Washington. The 8th District, which had been a swing district in the suburbs of Seattle, was expanded into central Washington to, essentially, make it a GOP stronghold. The 2nd District was also made stronger for Democrats by narrowing it to include left-leaning island counties.
The commission made the 1st District, which spans from suburban high-tech areas in King County to more rural areas of Snohomish, Whatcom and Skagit counties, to be competitive. Democrat Rep. Suzan DelBene clinched the seat with 54 percent of the vote in 2012. President Barack Obama won it with the same margin.
State Republican Party chairwoman Susan Hutchison said Republicans can compete in the 1st and 10th districts.
"I believe Washington is a swing state," she said. "The definition of a swing state is that half of your congressional districts are Republican and half are Democrat. Right now it's four and six, and if we pick up one, it'd be split. That's the definition of a swing state."
Under the current map, there are two districts that can be considered competitive, Donovan said. While he lauded that, he pointed out that after the 2000 redrawing, the state had three competitive districts out of nine.
Still, the advantage of gerrymandering and incumbency is a long-debated topic among political scientists, Donovan added.
"It's hard for us to model out and separate the effect of the gerrymandering process, campaign financed advantages and name recognition advantages," Donovan said. "If you're an incumbent for one day, you start accumulating these advantage that scare off challenges. DelBene has already $1 million bucks and she hasn't tapped into her own money yet."
Not everyone was happy with the commission's map in 2012. Vancouver resident John Milem, who was perhaps the only person to attend every redistrict public meeting, sued, contending the maps give too much power to King, Snohomish, Pierce, Thurston and Kitsap counties, which dominate seven of the state's 10 congressional districts. He also says the state Redistricting Commission split some cities and counties unnecessarily.