DES MOINES — In a locked windowless chamber across the street from the Iowa State House, three bureaucrats sequester themselves for 45 days every decade after census data is released. Their top-secret task: the “redistricting” of the state’s legislative and congressional boundaries.
But here, unlike in most other states, every care is taken to ensure the process is not political.
The mapmakers are not allowed to consider previous election results, voter registration, or even the addresses of incumbent members of Congress. No politician — not the governor, the House speaker, or Senate majority leader — is allowed to weigh in, or get a sneak preview.
Instead of drawing lines that favor a single political party, the Iowa mapmakers abide by nonpartisan metrics that all sides agree are fair — a seemingly revolutionary concept in the high-stakes decennial rite of redistricting.
Most other states blatantly allow politics to be infused into the process, leaving the impression — and sometimes the reality — that the election system is being rigged. And it has long, maybe always, been this way. The infamous gerrymander, after all, was coined in 1812 after Massachusetts Governor Elbridge Gerry signed a law that allowed a salamander-shaped district that benefited his party.
But some believe that partisan practice is now helping take the country over the edge, that extremism and gridlock are byproducts of politically motivated redistricting.
In the 2012 election, for example, Democrats nationally won 1.4 million more votes than Republicans in US House races, but Republicans won control of the House by a 234-201 margin — a lopsided result that some blame on redistricting.
A typical example, profiled earlier this year by the Globe, came in North Carolina, where a Republican-controlled legislature redrew district boundaries; Democrats there won 51 percent of the US House vote but were awarded only four of 13 seats.
By comparison, in Iowa, with its impartial way of drawing congressional districts, the results are viewed as a model of equity — and a model for the nation.
After the 2011 round of redistricting, the state’s four-person congressional delegation is evenly split between Democrats and Republicans.
Moreover, Iowa’s system has led to some of the nation’s most competitive races. In a country where the vast majority of members of Congress coast to reelection, Iowa’s races are perennial tossups.
The current system was enacted by the state Legislature in 1980 in a near-unanimous vote when Republicans held control of both chambers as well the governorship.
At the time, Republicans wanted to have a redistricting plan in place that would protect the minority party in the event the GOP lost in 1980, and Democrats agreed out of concern that their own party could be the one to lose. The bill assigned the task of drawing legislative boundaries to a nonpartisan, independent agency called the Legislative Services Agency.
“This puts the voter as the primary consideration,” said Ed Cook, the agency’s unassuming legal counsel who leads a mapmaking team that also includes two geographers. “The basic concept is if it’s a blind process, the result will be fair.”
The state’s 99 counties are divided into four congressional districts nearly equal in population,with each district drawn to include a mix of urban and rural interests. From the cornfields dotting most of the state to the university towns of Ames and Iowa City, the focus is on making sure residents have a voice, not on protecting an incumbent or political party.
This is done by making population size the primary metric when determining a district’s boundaries, followed by the goal of compact, contiguous districts that respect county lines.
“Having a more competitive district encourages somebody to really try to represent not just the ideology of his or her party but to represent the people of the district,” said Iowa’s governor, Terry Branstad.
Iowans say that the politically motivated redistricting in many other states pushes candidates to the extremes.
“Right now in the Republican Party you could be to the right of Attila the Hun and you’re more worried about somebody else who is further right than you are about the opposing party,” said Stephen Roberts, a Des Moines attorney who led the Iowa Republican Party when the state instituted the current redistricting system.
“People are less likely to compromise in Washington if they’re in safe districts,’’ Roberts said. “A classic example is gun control. People would rather face the ire of the voters than the ire of the NRA.”
One of the country’s hardest fought races in 2012 occurred between two longtime incumbents vying to represent the swath of southwest Iowa stretching from the capital city of Des Moines to the borders of Missouri and Nebraska.
After redistricting, Tom Latham, a 10-term Republican and close friend of House Speaker John Boehner, learned that his district’s boundaries had changed. So he moved 40 miles south from his four-bedroom home in the college town of Ames into a townhouse in the Des Moines suburb of Clive, putting him in a different district where he could avoid a primary challenge by fellow Republican incumbent Steve King.
Latham eked out a 52 percent win over Leonard Boswell, a Democrat who, for 16 years, had represented what was known as the Third Congressional District that was significantly redrawn. The district is now pretty evenly split among Republicans, Democrats, and Independents.
“The system in Iowa, while it isn’t always the greatest thing for the candidates themselves because it does cause competitive races throughout the state, at least forces everyone to actually communicate and to hear all points of view,” Latham said.
Even Boswell, a farmer who himself has moved in the past due to redrawn boundaries, holds no grudge against Iowa’s tradition of nonpartisan redistricting. “The negative impact on Republicans and Democrats has been pretty well-balanced over time,” Boswell said. “It’s works pretty good. More states should do it.”
King, a Tea Party member who represents Iowa’s most Republican district in the state’s northwest corner, said his new district map included more left-leaning votes than he would have liked.
“When I looked at the map, I wanted to challenge it,” said King, one of the most conservative members of Congress. “Who doesn’t want a map that’s more solid for their ideology? But it’s the right thing to have a redistricting plan designed to bring about the will of the people. If that means at some point I lose my seat in Congress because the redistricting plan disadvantages me in the long haul, the country is better off because it brought about the will of the people. ”
Some political scientists say Iowa’s system would be difficult to replicate in other states with larger, more diverse populations because they must adhere to the Voting Rights Act and create districts with significant minority representation.
While Congress has the power to change the way redistricting is done, proposals have gone nowhere in part because such changes might cost lawmakers their jobs.
“My colleagues like it just the way it is,” Latham said. “The majority of them are all safe. That’s the problem.”Tracy Jan can be reached at email@example.com. Follow her on Twitter @GlobeTracyJan.