"The American people have once again given the House of Representatives to Republicans," Rep. Pete Sessions (R-Texas), chairman of the House GOP's campaign arm, said at a victory party in the capital.
Among them: Democrat Tammy Duckworth, an Iraq war veteran who defeated Republican Rep. Joe Walsh, a tea party favorite, in Illinois. And Joseph P. Kennedy III, the grandson of Robert F. Kennedy; his election to succeed Rep. Barney Frank of Massachusetts will mark the return of a member of the storied family to Congress.
With all 435 House seats up for grabs, 62 had no incumbent running, the most since 1992, said David Wasserman, House editor at the nonpartisan Cook Political Report.
Although Democrats failed to win control of the House, Rep. John Barrow of Georgia withstood a strong GOP challenge to remain the last white Democrat in the House from the Deep South.
Democrats knocked off Republican incumbents in Florida, Maryland, New Hampshire and New York.
Republicans, in turn, defeated Democratic incumbents in Kentucky, Pennsylvania and North Carolina.
In Iowa, Rep. Steve King, a prominent hard-liner on illegal immigration, beat back a strong challenge from Democrat Christie Vilsack, wife of Agriculture Secretary and former Iowa Gov. Tom Vilsack.
The election could create the first House Democratic caucus without a white-male majority, according to Wasserman. And it could create a more polarized House, political experts say.
Republicans hold a 240-190 majority in the House, with five vacancies, three previously held by Democrats and two by Republicans. The margin separating the parties was expected to shift by only a few seats.
"Democrats look likely to defeat many Republican incumbents, but some of their own incumbents will also lose; hence, lots of movement, but not much net change," said Kyle Kondik, House editor at the University of Virginia Center for Politics.
In California, the balloting, combined with changes to the state's political system and a spate of retirements, was expected to produce the biggest turnover in its congressional delegation in 20 years.
There were at least 10 competitive races in a state where only one seat flipped between the parties in the last decade.
Battles between veteran Republican Rep. Dan Lungren and Democrat Ami Bera in a Sacramento-area district and between Republican Rep. Brian P. Bilbray and Democrat Scott Peters in a San Diego County district drew more than $8 million each in outside spending, among the most of any House races.
A new political map, drawn for the first time by an independent citizens commission instead of politicians, and the state's new top-two primary system set up clashes between members of the same party. The most noteworthy was a slugfest between Democratic Reps. Howard L. Berman and Brad Sherman in a San Fernando Valley race that drew more than $13 million in spending by the candidates and outside groups. Partial election returns showed Sherman with the edge.
Voters in New Hampshire gave that state an all-female congressional delegation, with Democrat Ann McLane Kuster defeating Republican Rep. Charles Bass and Democrat Carol Shea-Porter defeating Republican Rep. Frank Guinta. Both of the state's U.S. senators are women.
Mia Love fell short in her bid to become the first black Republican woman elected to the House, losing to Rep. Jim Matheson, a leader of a shrinking group of conservative Democrats known as Blue Dogs.
In one of the costliest, and nastiest, races in the country, Florida Republican Rep. Allen West, a tea party favorite, was trailing Democrat Patrick Murphy.
In Minnesota, former GOP presidential candidate Michelle Bachmann was leading Democrat Jim Graves, who had said the incumbent was "distracted by her own celebrity."
And in Arizona, Democratic Rep. Ron Barber, a former aide to former Rep. Gabrielle Giffords and a fellow shooting survivor who won a special election to succeed his boss, was locked in a tight race with Republican Martha McSally.
Political experts were trying to make sense of the lack of change, considering that a recent Gallup poll showed nearly 4 out of 5 Americans disapproved of the job Congress was doing.
"If there's anything historic about this election, it's going to be that with a [dismal] approval rating, we end up with no change?" said Norman Ornstein, an expert on Congress at the American Enterprise Institute.