Every decade, following the decennial census, the state legislatures of the United States are told how many representatives their state will send to the United States House of Representatives. Representation in the House is based on state population and there are a total of 435 representatives, so some states may gain representatives while others lose them. It is the responsibility of each state legislature to redistrict their state into the appropriate numbers of congressional districts.
Since a single party usually controls each state legislature, it is in the best interest of the party in power to redistrict their state so that their party will have more seats in the House than the opposition party. This manipulation of electoral districts is known as gerrymandering.
In the last 10 years, 78% of the seats in the U.S. House of Representatives, almost four out of every five members of Congress did not change party hands even once. In California, with 53 seats, the most in the nation, incumbents were kept so safe that only one of those seats changed party control in the past decade.
David Wasserman, a redistricting expert for the nonpartisan Cook Political Report, says only 20 races for Congress are expected to be tossups in the 2012 election. That's only 20 out of the 435 seats in the House. "In general elections, it's almost rigged," he said.
The lines for seats in Congress are redrawn every 10 years after the U.S. Census measures population shifts. That process is going on now in states across the country.
Race has been used to create a political divide in the South. In South Carolina, Georgia, Alabama, Mississippi and Louisiana only nine Democrats are left in Congress. Only one is white. He is Georgia Democrat John Barrow, and Republican control in that state's legislature has led to his home city of Savannah being excluded from his current district.
In 2010, Republicans captured control of North Carolina's legislature for the first time since shortly after the Civil War. They drew district lines in a way to pack 49% of all of North Carolina's African-American voters in just three of the state's 13 congressional districts. That left the other 10 districts mostly white and predictably Republican.
After the GOP landslide in 2010, Illinois is the only battleground state winning or losing a seat where Democrats remain in control. Nowhere is gerrymandering more apparent than in Chicago's 4th District, where a grassy strip hardly a football field wide, stuck in between two expressways, connects the top and bottom halves of a district designed to keep a Hispanic in Congress.
In California voters have revolted. In 2010, they passed an amendment to the state constitution to take redistricting out of political hands and have a commission of citizens redraw the lines. It was forbidden to favor incumbents. As a result, more than half of California's 53 representatives were placed in the same district with another colleague for the 2012 election. As many as 15 could lose or else face retirement to avoid losing.
For three decades now, Iowa has had a nonpartisan redistricting system. Two legislative staffers draw the maps in secrecy without political interference. "In Iowa, it is understood incumbent protection is not the name of the game," one of those staffers said. Iowa, with its regular-shaped districts, will host the only 2012 House face off between Democratic and GOP incumbents. Iowa has the nation's only congressional race next year where a longtime Republican incumbent, Tom Latham, is paired against a longtime Democratic incumbent, Leonard Boswell.
Computers and GIS were utilized in the 1990 and 2000 Census by the states to make redistricting as fair as possible. Despite the use of computers, politics does get in the way and many redistricting plans are challenged in the courts, with accusations of racial gerrymandering tossed about. We certainly won't expect accusations of gerrymandering to vanish anytime soon.