In a months-long general election ad war that cost nearly $1 billion, Romney and Republican groups spent more than $550 million and Obama and his allies $381 million, according to organizations that track advertising.
In Virginia, the polls had been closed for several minutes when Obama's campaign texted a call for volunteers "to make sure everyone who's still in line gets to vote."
In Florida, there were long lines at the hour set for polls to close. Under state law, everyone waiting was entitled to cast a ballot.
According to the exit poll, 53 percent of voters said Obama is more in touch with people like them, compared to 43 percent for Romney.
About 60 percent said taxes should be increased, taking sides on an issue that divided the president and Romney. Obama wants to let taxes rise on upper incomes, while Romney does not.
Other than the battlegrounds, big states were virtually ignored in the final months of the campaign. Romney wrote off New York, Illinois and California, while Obama made no attempt to carry Texas, much of the South or the Rocky Mountain region other than Colorado.
There were 33 Senate seats on the ballot, 23 of them defended by Democrats and the rest by Republicans.
Democratic Rep. Chris Murphy, a Democrat, won a Connecticut seat long held by Sen. Joe Lieberman, retiring after a career that included a vice presidential spot on Al Gore's ticket in 2000. It was Republican Linda McMahon's second defeat in two tries, at a personal cost of $92 million.
The GOP needed a gain of three for a majority if Romney won, and four if Obama was re-elected. Neither Majority Leader Harry Reid of Nevada nor GOP leader Mitch McConnell of Kentucky was on the ballot, but each had high stakes in the outcome.
All 435 House seats were on the ballot, including five where one lawmaker ran against another as a result of once-a-decade redistricting to take population shifts into account. Democrats needed to pick up 25 seats to gain the majority they lost two years ago.
Depending on the outcome of a few races, it was possible that white men would wind up in a minority in the Democratic caucus for the first time.
Speaker John A. Boehner, R-Ohio, raised millions to finance get-out-the-vote operations in states without a robust presidential campaign, New York, Illinois and California among them. His goal was to minimize any losses, or possibly even gain ground, no matter Romney's fate. House Democratic leader Rep. Nancy Pelosi of California campaigned aggressively, as well, and faced an uncertain political future if her party failed to win control.
In gubernatorial races, Republicans picked up North Carolina, where Pat McCrory won easily. The incumbent, Democratic Gov. Bev Purdue, did not seek re-election.
In a campaign that traversed contested Republican primaries last winter and spring, a pair of political conventions this summer and three presidential debates, Obama, Romney, Biden and Ryan spoke at hundreds of rallies, were serenaded by Bruce Springstein and Meat Loaf and washed down hamburgers, pizza, barbecue and burrito bowls.
Obama was elected the first black president in 2008, and four years later, Romney became the first Mormon to appear on a general election ballot. Yet one man's race and the other's religion were never major factors in this year's campaign for the White House, a race dominated from the outset by the economy.
Over and over, Obama said that during his term the nation has begun to recover from the worst recession since the Great Depression. While he conceded progress has been slow, he accused Romney of offering recycled Republican policies that have helped the wealthy and harmed the middle class in the past and would do so again.
Romney countered that a second Obama term could mean a repeat recession in a country where economic growth has been weak and unemployment is worse now than when the president was inaugurated. A wealthy former businessman, he claimed the knowledge and the skills to put in place policies that would make the economy healthy again.
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