Barack Obama is the first president in more than five decades to win at least 51 per cent of the national popular vote twice, according to a revised vote count in New York eight weeks after the November 6 election.
State election officials submitted a final tally on December 31 that added about 400,000 votes, most of them from provisional ballots in the Democratic stronghold of New York City that were counted late in part because of complications caused by hurricane Sandy.
Nationally, Mr Obama won 65.9 million votes, or 51.1 per cent, against Republican challenger Mitt Romney, who took 60.9 million votes and 47.2 per cent of the total cast, according to data compiled by Bloomberg.
Mr Obama is the first president to achieve the 51 per cent mark in two elections since the Republican Dwight Eisenhower, who did it in 1952 and 1956, and the first Democrat to do so since Franklin Roosevelt, who won four consecutive White House races. Mr Roosevelt received 53.4 per cent of the vote - his lowest - in his last race in 1944.
Mr Obama, 51, benefited from political factors that included a lack of serious opposition for his party's nomination or from well-known third-party challengers, and an absence of social unrest, scandal or foreign-policy disasters during his first term, said Allan Lichtman, a history professor at American University in Washington.
''Under the big picture, this was an entirely predictable election outcome,'' Professor Lichtman said.
The President won the popular vote in 26 states and the District of Columbia, totaling 332 electoral votes, or 62 more than the 270 needed to win the presidency. Mr Romney won 24 states with 206 electoral votes. Mr Obama won 365 electoral votes in 2008.
Mr Obama will take the oath of office on January 20, a Sunday, and give his inauguration speech at the Capitol on January 21.
Turnout in this year's presidential race was about 129.1 million, down from the record 131.3 million four years ago.
Mr Obama's vote total fell by about 3.6 million votes from his record 69.5 million in 2008, when he was elected the nation's first black president.
In that race he won 52.9 per cent - with a victory margin of more than 9.5 million votes over the Republican candidate, John McCain - amid a financial crisis that took hold at the end of George W. Bush's presidency.
The unemployment rate, 7.8 per cent when Mr Obama succeeded Mr Bush in January 2009, rose to 10 per cent that October before falling to 7.7 per cent last November.
Mr Obama is the second president since World War II to win re-election with a jobless rate above 6 per cent. The other was the Republican Ronald Reagan in 1984.
''He was able to campaign against the economy back in 2008 because it was Bush's problem,'' the political analyst Rhodes Cook said. ''It got reversed. He got stuck with the economy this time.''
Mr Romney, a former private-equity executive and governor of Massachusetts, failed to parlay voter anxiety about the economy into a victory.
While Mr Obama's national vote percentage fell by about 2 points from four years ago, he improved on his 2008 performance in six states, including New York, where his 63.3 per cent was the best by any presidential nominee since 1964.