A gerrymander is the drawing of voting districts for the advantage of one party over its opponents.

The term originated in 1812, when Massachusetts Gov. Elbridge Gerry signed into law a bill that created a state Senate district map designed to give his Democratic-Republican Party a large majority in that chamber, with the opposition Federalist Party's voters heavily concentrated in only a handful of districts.  One of the districts had a strange shape, with some claiming it looked like a salamander.  A guest at a dinner party suggested that it be called a gerrymander, and the name has stuck ever since.

Congressional districts are reapportioned every 10 years to reflect population shifts discovered by the census, and Democrats and Republicans have taken turns at drawing Michigan's district map to their advantage when they have been able to control the process. 

The best evidence of a gerrymander occurs when a party wins a majority of seats in the state's congressional delegation while losing the statewide congressional vote.  As examples, Republicans won 12-7 majorities in 1968 and 1970 while Democrats won the statewide vote, and Democrats won a 9-7 majority in 1994 while Republicans won the statewide vote.

The 1990s districts generally favored the Democrats, who won at least nine seats in every election, while Republicans won at least six every time.  The remaining district, the Lansing-based 8th, went back and forth.  Four of the Democrats in their nine districts, Reps. Dale Kildee, Sander Levin, David Bonior and Lynn Rivers, had close races at times, while none of the Republicans in their six districts were ever seriously threatened. 

But in 2002, Republicans had control of the redistricting processs and took full advantage.  Because Michigan's population had grown slower than the national average, the state lost a seat.  But Republicans were still able to gain two seats for a 9-6 majority in Michigan's congressional delegation.

In drawing the districts, Democratic Reps. Kildee and James Barcia were thrown together in the 5th District, Levin and Bonior both found themselves in the 12th District, and Rivers and John Dingell wound up in a primary fight in the 15th District.  Two open districts designed to elect Republicans were created, the 10th, won by Candice Miller, and the 11th, which elected Thaddeus McCotter.  The 8th District, which kept Democratic Ingham County and Republican Livingston County, was made safely Republican by removing Democratic voting areas at its periphery and replacing them with Republican territory.  As a result, Republican Rep. Mike Rogers, who barely won in 2000, was easily re-elected.

Republicans kept their 9-6 majority despite losing the statewide congressional vote in 2002 and 2006.  But sometimes voting patterns can shift, and a gerrymander can fail to achieve its purpose.  A Democratic trend in the Detroit suburbs and outstate resulted in close races in 2006 for Republican Reps. Joe Knollenberg in the 9th District and Tim Walberg in the 7th District, and both were defeated in 2008, giving the Democrats an 8-7 majority.

At the same time, McCotter's percentage of the vote has declined since his first election to the point that he had a close race in 2008.  He has now been targeted for defeat in 2010 by the Democratic Congressional Campaign Committee.

The next census will also take place in 2010, with redistricting to follow in 2012.  But which party will control the reapportionment process and attempt a gerrymander remains to be seen.