LANSING, Mich. — Michigan's 14th congressional district looks like a jagged letter "S" laying on its side.
From Detroit, one of the nation's most Democratic cities, it meanders to the west, north and east, scooping up the black- majority cities of Southfield and Pontiac while bending sharply to avoid Bloomfield Hills, the affluent suburb where 2012 Republican presidential nominee Mitt Romney was raised.
Its unusual shape is intentional. Michigan Republicans, seeking to maximize their political strength, drew the district lines — and the residential patterns of Democratic voters made their job easier.
Michigan's 14th district underscores how Democrats nationwide are bunched in big metropolitan areas, resulting in the party's House candidates often winning by wide margins on Election Day while Republicans capture more seats because their voters are spread out.
It's a prime reason Democrats fell 17 seats short of winning a House majority in 2012, even as their congressional candidates drew about 1.4 million more votes than Republicans nationwide, according to data compiled by Bloomberg News. And it will hinder the Democrats from regaining control of the chamber in 2014. The House now has 232 Republicans and 200 Democrats, with three vacancies.
"A big part of why Republicans are able to win a majority of congressional seats, even in swing states, is because of very inefficient geographic concentration of Democratic voters, particularly in urban areas," said Jowei Chen, a political scientist at the University of Michigan in Ann Arbor.
The election results mean House Republicans will have the power to block or demand amendments to President Barack Obama's agenda.
That tension between a White House controlled by one party and a House run by another will be on display during the deficit reduction talks in coming months as Obama advocates a combination of spending cuts and new revenues. That position was favored by 67 percent of Americans in a CNN/Orc International poll conducted Nov. 16, two weeks after voters re-elected Obama. Republican House members this month unveiled a budget that would eliminate the deficit in 10 years by cutting $4.6 trillion and using no new tax revenue.
Before Obama, all but five of the last six elected presidents — the exception was Jimmy Carter — had a House controlled by the opposition party at some point during their tenure.
But it's rare for one party to win more House seats while securing fewer votes than the other party. The last time it happened before 2012 was in 1996, when Democrats won the nationwide House vote by 43.6 million to 43.4 million as Republicans held their majority and Bill Clinton was re-elected president, according to the House Clerk's office.
The variance between the nationwide partisan vote total for House candidates and the Republican-Democratic seat split in the chamber is caused by demographics and redistricting, the once-a- decade redrawing of political boundaries that Republican- controlled statehouses dominated following the 2010 census.
Redistricting is intended to ensure House members represent roughly equal size populations. Yet from the first Congress, party leaders began exploiting the map-making exercise by weakening the voting strength of some groups to gain partisan advantage, a practice known as gerrymandering.
Urban cores are packed with black, Hispanic and single white voters who, exit polls show, voted strongly Democratic in 2012. As of 2011, half of all Hispanics were concentrated in 30 of the nation's more than 3,100 counties; half of all blacks lived in 60 counties, said William Frey, a senior fellow at the Brookings Institution's Metropolitan Policy Program in Washington.
When Republicans control redistricting, they can pack Democrats into a limited number of districts while maximizing, with computer precision, their party's advantage in other House races.
State lawmakers can build databases with detailed voter registration figures, election results and population data to project campaign outcomes and demographic trends. It's also easier to predict voting patterns since fewer than 30 districts backed the presidential candidate of one party and a House candidate of the opposite party in 2012 — the lowest rate in at least 90 years, according to data compiled by Bloomberg.
Republicans exploited their advantages in Florida, Ohio, Pennsylvania and other states.
Michigan provides one of the best illustrations of how demographic shifts and gerrymandering combined to give Republicans the upper hand.
They swept all three branches of state government in 2010 to seize control of redistricting. At the same time, Michigan's House delegation needed to shrink to 14 members from 15 because of population losses recorded in the 2010 Census.
The result in the 2012 elections: Republicans won nine of 14 House seats, even though Obama carried the state by more than 9 percentage points and the combined vote for Democratic House candidates totaled about 2.3 million compared to 2.1 million for the Republicans.
Michigan's five Democratic House members each won with at least 61 percent of the vote, and two got more than 82 percent in districts that include portions of Detroit, the state's largest city that is 82 percent black and 7 percent Hispanic.
Only three of the state's nine Republicans in the House topped 60 percent of their district vote. Five of them received less than 55 percent.
A district should have a spread of no more than five percentage points between Democratic and Republican voters to be competitive, said Jocelyn Benson, a voting rights advocate and interim dean of Wayne State University's Law School in Detroit.
In 2012, only one Michigan district met that standard. Republican Dan Benishek won a second term in it with 48.1 percent of the vote compared to 47.6 percent for his Democratic opponent. The largely rural district encompasses the state's northern-most areas, including the Upper Peninsula.
One district in which Democratic voters dominate comprises a swath of Detroit's north suburbs and is represented by Sander Levin, a 16-term Democrat and the brother of one of the state's senators, Carl Levin. Sander Levin, 81, won re-election in November with 61.9 percent of the vote.
The district is anchored by Warren, Michigan's third largest city with about 134,000 residents. It has the GM Technical Center and two auto plants, a median income of $45,400 and a lower percentage of college graduates than the statewide average.
Warren in the 1980s was a hotbed of so-called Ronald Reagan Democrats — predominately white voters who defected from their political roots to support the Republican president.
More recently it's a place where minorities, especially African Americans, are migrating. Many of them have come from Detroit, which the 2010 census showed lost 25 percent of its population during the preceding 10 years. Blacks comprise 13.5 percent of Warren's population, up from 2.7 percent in 2000.
Also fueling the community's demographic change was the departure of some Republican voters for more distant suburbs. As more blacks have relocated to Warren, so have Democratic-leaning younger voters, said state senator Steve Bieda, a Democrat who represents the area.
"They seem to be more progressive in their views on social issues," Bieda said.
Jocelyn Howard, a Detroit native and black Democrat, moved to Warren eight years ago. Howard, who's single and in her 40s, said the community once had a reputation as hostile to blacks. Since she bought a house in the first new subdivision built in the city in 50 years, she said she has felt welcome and a sense of belonging.
Warren's lifestyle, rather than political considerations, attracted Howard: safety, good schools and affordable, well- maintained homes. The upshot is that she and other like-minded newcomers have altered the city's political complexion.
In the 1988 presidential race, Warren went for Republican George H.W. Bush over Democrat Michael Dukakis, 57 percent to 43 percent. Obama carried the city in 2012 with 61 percent of the vote.
The new House districts don't reflect Michigan voters, Levin told reporters at a Feb. 26 Bloomberg Government event. He said the state should create an independent commission to handle redistricting.
"In the '90s, there were four or five marginal seats in Michigan, and I was in one of them," Levin said. "I had tough races four times in a row. That's much better."
Competitiveness is not required by Michigan's redistricting rules, said State Rep. Peter Lund, a Republican who led the Michigan House committee redrawing the congressional map. Complaints about the Republican success in packing Democrats into districts to minimize the party's success ring hollow to him.
"I understand Democrats don't like" the reconfiguration, he said. "If they were the ones drawing the maps, I'm sure we wouldn't like what they drew."
The districts he and other Republicans crafted and that Gov. Rick Snyder signed into law reflect that "Democrats tend to live in areas that are more Democratic," Lund said. Also, requirements under the federal Voting Rights Act to maintain two Detroit-centered districts in which minorities are a majority of voters influenced the process.
What Republican-controlled redistricting did in Michigan occurred in other states. In Ohio, with Republicans shepherding the redistricting process, the party won 12 of 16 districts even though Obama won the state by two percentage points.
In Florida, just six of 67 counties gave Obama more than half of his votes, three of them in the Miami area. As the president carried Florida by just shy of one percentage point, Republicans won 17 of 27 congressional districts.
The clustering of Democrats in urban areas, including in disproportionately black and Hispanic districts as mandated by the federal law, hinder the party as it seeks a majority of House seats, said Tom Davis, a former Virginia representative who led the National Republican Congressional Committee during the 2000 and 2002 campaigns.
"If you wanted to carve it up to the Democrats' advantage, you can't," said Davis. "You just go miles and miles with nothing but Democrats, and that hurts them."