The week before the election, a Washington Post report said 44 per cent of all likely voters had been contacted by the Obama campaign in the toss-up state of Virginia, whose 13 electoral votes went to Obama on election night. (More than 41 per cent were contacted by the Romney campaign, still an impressive figure.)
There is anecdotal evidence galore of the strength of the ground campaign. During interviews with Obama supporters attending a rally in Bristow, Virginia, at the weekend, African American voter Laurie Franklin said that a Democratic activist knocked on her door "and registered me right there".
The effort to bring out the vote by both parties was intensive using personal interviews, phone banks and robocalls.
Both campaigns used Facebook and the full gamut of social media for the first time, using website tracking to get out the vote and appeal to new voters.
The National Association for the Advancement of Coloured People said "tens of thousands" of additional black voters - part of the President's core constituency which voted for him almost universally in 2008 - had been registered in Virginia. By tending to his coalition of voters, Obama won the election by 93 per cent of African Americans, 70 per cent of Hispanics and 70 per cent of Asians.
Time magazine described Obama campaign manager Jim Messina's strategy of setting up a data analysis team five times the size of the one in the 2008 campaign. But "public details were in short supply as the campaign guarded what it believed to be its biggest institutional advantage over Mitt Romney's campaign: its data".
The data mining helped Obama raise US$1 billion via email appeals to targeted voters based on their profiles. It also remade the process of targeting TV ads and "created detailed models of swing state voters that could be used to increase the effectiveness of everything from phone calls and door knocks to direct mailings and social media".
Resources were allocated where the data pointed. "We had a good organisation in '08," said senior adviser David Plouffe. "This organisation is light years ahead of that."
At every campaign stop, the President told supporters the result "depends on you", as he urged volunteers to get out the vote.