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.