Barack Obama has been re-elected US president for a second term as the challenge of Mitt Romney fell by the wayside this morning.
As the win was announced by TV networks across America, President Obama tweeted his gratitude to his supporters, hailing 'four more years' and posting a picture of himself locked in an embrace with his wife Michelle.
President Obama, addressing crowds in Chicago after Romney officially conceded, said: "For the United States of America, the best is yet to come.
"It moves forward because of you. You reaffirmed the spirit that has triumphed over war and depression."
In a tribute to his wife, Obama said: "I want to say this publicly: Michelle, I have never loved you more.
"I have never been prouder to watch the rest of America fall in love with you too as our nation's first lady."
Obama continued a rousing victory speech by calling for unity in America and pledging to "return to the White House more determined and inspired than ever."
Obama also congratulated Romney on a 'hard-fought campaign'.
He said: "We may have battled fiercely, but it is only because we love this country so deeply."
In Mitt Romney's concessionary speech in Boston he told his supporters: "I have just called Obama to congratulate him on his victory."
He went on to thank his VP nominee Paul Ryan and his wife Ann, who he said "would have been a great first lady".
Romney added Obama faced major challenges. "I pray the president will be successful in guiding our nation", he said.
Republican Romney needed to win the key swing states of Ohio, Florida and Virginia to stand a chance of an overall victory.
But Obama's victory in the hotly contested Ohio - as projected by TV networks - put him over the 270 electoral votes needed to clinch the White House.
Obama secured the narrowest of wins in Ohio, Iowa, Pennsylvania, Wisconsin and New Hampshire - while the only swing state captured by Romney was North Carolina, according to network projections.
The atmosphere at Obama's Chicago election night rally was electric as crowds cheered the Obama win, while at Romney's Boston event streams of people left the ballroom as the news came through.
Opinion polls before today's vote casting showed Obama and Romney neck-and-neck.
Around 120 million Americans were expected to register their votes today to determine whether Obama would earn a second term.
Obama and Republican Romney were offering distinctly different policies to boost America's faltering economy, with Obama pledging to raise taxes on the rich and Romney promising wide-ranging tax cuts as a way to power the US forward.
In the final 24 hours Romney made visits to Pennsylvania and Ohio to try and ramp up the turnout in those states, while Vice President Joe Biden was sent to Ohio. Obama stayed in his hometown of Chicago.
A bullish Romney told reporters on his aeroplane as he flew back to Boston he had written only a celebration speech.
He said: "I'm very proud of the campaign that I've run, to tell you the truth.
"I'm sure like any campaign, people can talk to mistakes, but that's going to be part of anything that's produced by human beings."
Meanwhile, Obama told reporters he had speeches ready for either outcome.
Speaking to Denver television station FOX31, he said: "You always have two speeches prepared because you can't take anything for granted."
The nation's first black president was seeking to avoid serving just a single term - something that has happened to only one of the previous four occupants of the White House.