However, "Democrats had figured out the map they wanted to end up with and then they went to community groups and made the pitch to get that," said Douglas Johnson, a fellow at the Rose Institute of State and Local Government at Claremont McKenna College.

So a process that was supposed to be random wasn't completely.

"It was a huge improvement over the legislature drawing the lines," Johnson said. "It didn't measure up to the grand hopes and nirvana dreams of some, but it was an improvement."

Thirteen states have adopted some version of commissions to try to remove politics from redistricting, a task some political scientists and demography experts say is impossible and doesn't necessarily result in more balanced districts in this hyper-polarized climate.

"Given the breakdown of traditional institutions and the traditional ways people mix, how do you govern this new country?" asked Bill Bishop, co-author of "The Big Sort: Why the Clustering of Like-Minded America is Tearing Us Apart."

"How do you create one country out of a country that is becoming increasingly a collection of communities?"

The house we built

Increasingly, people live in communities that are carefully crafted political echo chambers.

"The dirty little secret is that redistricting only explains part of polarization," Wasserman said. "Congressional districts are polarized partly because Americans have polarized with their feet. It makes it easier for partisan line drawers to draw those lines."

Every 10 years, just after the U.S. Census is completed, state lawmakers are charged with the task of redrawing and, in some cases, creating congressional districts that take into account population shifts since the last census. It is often a deeply partisan and complicated process in which the party in power usually tries to craft districts that are favorable to them while minimizing the other side's political heft.

A number of states, many of them in the South, with a history of racially discriminatory voting practices, also must get pre-clearance from the Department of Justice before tweaking their voting laws and maps. In several places, efforts to achieve this equity have resulted in odd shaped districts and court challenges.

Take for example Watt's 12th District in North Carolina, a narrow, serpentine strip that nearly dissects the state as it snakes 80 miles along Interstate 85. The district is considered "majority minority" and is reliably Democratic.

"In states where Republicans have control, Republicans have been able to use the Voting Rights Act to pack (minorities) into districts so they can win the rest, Wasserman said.

But that only explains part of why some districts are so partisan.

Across the nation, people are self-sorting into neighborhoods and cities with likeminded peers, political experts and demographers say.

"We don't think people move to be around others who vote like themselves. They are moving to be around people who are like themselves in every other sort of way," Bishop said.

"Young white people moved to Austin. Young black people moved to Houston, Atlanta and D.C. Every time we looked at a measure on the country level, differences began to appear," Bishop said. "Civic groups became more specialized. Churches began to organize around lifestyles. Lifestyle characteristics began to line up with the vote."

In looking at election data from 1992, 2000 and 2002, political scientists Marc Hetherington of Vanderbilt University and Jonathan Weiler of the University of North Carolina at Chapel Hill found that places where spanking is more likely to be used to discipline children tend to lean Republican. Areas where timeouts are the norm tend to trend Democrat.

Women in the Northeast who married and started families later in life tended to vote Democrat while their Midwestern peers who got a head start on marriage and family building often voted Republican, Belgian demographer Ron Lesthaeghe found.

Large numbers of women, minority, gay and young voters helped President Barack Obama clinch his victory in the recent general election. Likewise, a historic number of women and racial minorities were elected to Congress from similarly diverse and largely Democratic states and districts.

On the other hand, Republican presidential contender Mitt Romney's strong performance among many white voters echoes his party's congressional representation --- largely older, white men.

During the 2012 election, Obama won technology hub Silicon Valley, continuing a trend of technocrats backing Democrats. But he lost the Deep South, continuing that region's red streak.

All of this self-sorting in tiny towns, urban enclaves and suburbs has had a collective impact on the rarefied and increasingly toxic political climate in Washington these days.

The 112th House was roughly 50% more polarized in terms of makeup than that of the 102nd, which convened from 1991 to 1993, Poole found in his research.

The 112th's Senate was more polarized than the 46th Senate, which was in office from 1879-1881, just after the Reconstruction era that followed the Civil War, Poole found.