U.S. President Barack Obama told the American people "the best is yet to come" after he defeated Republican challenger Mitt Romney to win re-election.
Obama thanked his cheering supporters in an early morning victory speech at his Chicago headquarters, telling them the "task of perfecting our union moves forward." He said "we are an American family and we rise or fall together as one nation and one people."
Obama also thanked his Republican challenger, Romney, and his vice presidential running mate, Paul Ryan, for waging a hard fought campaign. He said although he and Mr. Romney strongly disagreed on the issues, they both shared a deep love for the country.
Shortly before the president spoke, Romney conceded the race in a speech before a crowd of disappointed supporters in Boston, Massachusetts, the state he once governed. He congratulated Mr. Obama on his election victory, saying "this is a time a great challenge for our nation, and I pray the president will be successful in guiding our nation."
The latest projected results from Tuesday election have Mr. Obama, a Democrat, winning 303 electoral votes and Mr. Romney with 206 Electoral College votes. A candidate needs at least 270 electoral votes to win the presidency.
Obama won in the District of Columbia and 25 states, including the battleground states of Ohio, Virginia, Iowa, New Hampshire and Pennsylvania. Romney won in 23 states including North Carolina and Indiana, which both went for Obama last election. Another key battleground state, Florida, remains too close to call.
The candidates made a final push for support Tuesday as voters waited in long lines at polling places. Some sporadic problems were reported, and both candidates dispatched lawyers to monitor the voting for any irregularities.
The Justice Department had nearly 800 observers in 23 states to respond to any allegations of fraud.
After a year-and-a-half of campaigning, three debates and thousands of televised campaign ads, nationwide pre-election surveys had the two candidates in a virtual deadlock.
U.S. presidential elections are not decided by the national popular vote, but rather by the Electoral College system, developed more than 200 years ago, in which each of the 50 states' influence on the outcome is roughly equivalent to its population. The winner needs 270 electoral votes to win the White House.
Voters were also electing all 435 members of the House of Representatives, and 33 of the 100 members of the Senate.
US President Barack Obama celebrates after delivering his acceptance speech in Chicago on November 7, 2012.
President Barack Obama speaks at his election night party November 7, 2012, in Chicago, Illinois.
President Barack Obama walks on stage with first lady Michelle Obama and daughters Malia and Sasha at his election night party November 7, 2012, in Chicago, Illinois.
President Barack Obama waves as he walks on stage with first lady Michelle Obama and daughters Malia and Sasha at his election night party November 7, 2012, in Chicago, Illinois.
Republican presidential candidate Mitt Romney waves to supporters before conceding at his election night rally, November 7, 2012, in Boston, Massachusetts.
A supporter reacts to voting results displayed on a TV screen during Republican presidential candidate Mitt Romney's election night rally in Boston, Massachusetts, November 7, 2012.
Republican presidential candidate Mitt Romney and his wife Ann stand on the stage with Republican vice presidential candidate Paul Ryan,and his wife Janna during his election night rally, November 7, 2012, in Boston, Massachusetts.
Supporters of U.S. President Barack Obama cheer during his election night rally in Chicago, November 6, 2012.
Arizona Democrats celebrate as President Barack Obama is declared the winner of the presidential race at a Democratic Party gathering in Tucson, Arizona, Tuesday, Nov. 6, 2012.
A woman takes a photo of the Empire State Building that is lit up in blue, the color of the Democrat Party, after Barack Obama was projected to win the U.S presidential election in New York, Nov. 6, 2012.
Supporters of President Barack Obama react to favorable media projections at the McCormick Place during an election night watch party in Chicago, Tuesday, Nov. 6, 2012.
People pose with a picture of President Barack Obama during the Election Night Party 2012 following the U.S. Presidential Election, at the Intercontinental Hotel in Madrid, Spain.
Democrats celebrate reports that President Barack Obama won the election at the Ohio Democratic party election night celebration early Wednesday, Nov. 7, 2012, in Columbus, Ohio.
Ryan Charchian, 18, of New York, hugs Allie Rapa, 19, of New York after news reports projected President Barack Obama to win a second term as they celebrated in New York, Nov. 6, 2012.
People react as a television promoter announce results of the United States elections during a Presidential Election party hosted by the United States embassy and German Telekom in Berlin, Germany.
Guests look at early projections for votes for the President Barack Obama and Republican presidential candidate Mitt Romney during the Presidential Election party at the U.S. Embassy in London, England.
Projections Tuesday show Republicans will hold onto control of the House of Representatives while Democrats will stay in charge of the Senate.
Millions of Americans cast ballots in early voting in the last month. Obama voted several days ago in his home city of Chicago, and spent Tuesday there. He conducted interviews for broadcast in key states and played basketball with friends, one of his Election Day traditions. He also called voters from a campaign office.
Romney, a one-time venture capitalist, voted Tuesday morning in Massachusetts, the northeastern state he once governed but where Obama won. He also made a final push for votes in the key states of Ohio and Pennsylvania.