Midnight plus 43 seconds (all times Eastern Standard Time; equivalent to 05:00.43 GMT)
As is traditional, polling nationwide begins in the tiny New Hampshire village of Dixville Notch. There are only 10 voters and the count is over in less than a minute. Five votes are cast for each of the two candidates: the first tie in Dixville's history, setting a possibly ominous precedent for the hours to come. "It's going to be a wild ride," the town clerk Dick Erwin says. But there are other ways to spin it: this was also only the second time – 2008 being the first – that the Republican candidate had failed to carry the village. What's beyond dispute is that, for America as a whole, it is will be a long day. Not until after 7pm do the polling stations start to close and the first indications emerge of how the nation has been voting.
19:04 First polling stations close in Florida, New Hampshire and Virginia on the East Coast and the real counting gets under way. Mitt Romney tells reporters, "I only wrote one speech" – a victory one.
19:09 Exit polls in Virginia, one of the seven (or nine, or 11, depending on who you ask) crucial swing states in the race show a 49-49 split between the candidates: predictions of a nail-bitingly tight race seem on the money. "It doesn't get much closer than that," tweets veteran CNN anchor Wolf Blitzer.
19:21 Virginia is one of the states where the nation's changing demographics are most palpable, as the conservative South is counterbalanced by swelling Democrat-voting suburbs and ethnic voters. In 2008 Barack Obama won the state 52.6 to John McCain's 46.3 – now the exit polls put the candidates tied on 49:49, indicating a 3 per cent swing to Romney, and a tied popular vote nationwide.
19:32 In Ohio, the state that no Republican who went on to win the presidency has failed to hold – early exit polls give Obama a three-point lead. It's the auto bailout, stupid. In North Carolina, another of the swing states, exit polls are tied between the two candidates.
19:35 Romney wins Kentucky, giving him eight electoral votes, Obama wins Vermont giving him three. Associated Press: "An unsurprising start to the night." Romney also captures West Virginia, adding five to his electoral total.
19:42 It's revealed that 12.2 million Hispanics have voted in the election, 26 per cent more than in 2008.
20:00 Polls close in Ohio, the most critical state of all. It emerges that, in an election campaign that cost far more than any before it, $6bn (£3.8bn), Florida was the most profligate of the lot, throwing $167m-worth of electoral spaghetti at the wall.
20:04 A flurry of "calls" as Americans announce what we call projections; none of them is surprising. Massachusetts, Illinois, Washington DC, Maryland, Delaware, Rhode Island are all projected for Obama.
20:08 A delegation of accredited international election observers from Europe's Office for Democratic Institutions and Human Rights reports being barred from getting even close to polling stations, threatened with arrest and receiving "some unpleasant messages, euphemistically speaking". Reports in the US media claimed, wrongly, that they were UN agents bent on interfering with the polls. Europeans retreat, licking their wounds.
20:10 First indications that perhaps far less has changed in the past four difficult years than was claimed: in Ohio 96 per cent of blacks and 42 per cent of whites are voting for Obama, only a little below the figures for 2008.
20:14 Electoral college vote tally puts Obama on 51 and Romney on 40.
20:25 Chante Jones, prominent black businessman in Tampa, Florida, asks the million-dollar question: was Obama's victory in 2008 a fluke – revulsion after eight years of Dubya – or a paradigm shift? Soon we'll know.
20:27 British hack at the US Embassy's election night party in London tweets that a "top US pollster" says it's all over, blaming Romney's Mormonism for the low Republican turnout.
20:28 In the squeakiest state of the lot, Florida, Obama is reported to be gaining a slim lead of 50 to 49. In a bellwether precinct with 90 per cent of votes in, he is said to be clear by a full 6 per cent.
20:31 The tipsters seem to know more than the political pundits at this point: The Independent's Guy Adams tweets that Romney's odds on Betfair's online betting website are "falling fast, they just hit 17/2 – this race seems to be slowly slipping away". One minute later, however, AP has Romney edging Obama on electoral votes 67 to 65, from projections in 15 states.
20:36 Andrew Sullivan, blogging on The Daily Beast website, notes that, while Obama's share of the white vote in Ohio has slipped from 46 to 42 per cent, that is more than offset by a surge in the black vote. "If that is sustained, Obama has built a new coalition and wins the state and Pennsylvania. What's striking for me is that the black turnout is much bigger than expected."
20:41 NBC says Indiana – Republican in 2008, and not even on the swing state list – is too close to call. Republicans everywhere shift closer to the edge of their seats.
20:51 …and the bad news for Republicans is now coming in thick and fast: latest exit polls say Obama wins by 6 per cent in Nevada, 4 per cent in Wisconsin, 3 per cent in Ohio and 2 per cent in New Hampshire – all swing states Romney needs to hold if he is to win. Associated Press claims Obama could win Alabama, deep in the southern Republican heartland.
21:00 Polls close in Colorado, Wisconsin and parts of Michigan.
21:06 Hundreds of Republicans have gathered at a ballroom in Boston for Romney's election-night party, paying tens of thousands of dollars for the privilege. But the festive mood dies to pin-drop silence as Fox News, the GOP's broadcaster of choice, reports that he has lost his native state, Michigan, to Obama. Reporters with good memories dig out the reckless piece he wrote for The New York Times back in November 2008, headlined "Let Detroit Go Bankrupt".
21:09 Two more vital pieces in the night's fascinating demographic jigsaw: women are out-voting men, good for Obama as he has the edge with women. And in rural Virginia there is a big turnout of black voters for Obama. In that state Romney faces a pincer movement, with new suburban Democrats in the north and black country folk in the south squeezing the traditional Republican dispensation.
21:16 Republicans breathe again with good news from key swing states Virginia and Florida; Romney ahead in Florida's vote with 75 per cent counted. But the relief is short-lived – immediately both NBC and Fox call Pennsylvania for Obama. Romney's decision to buck tradition and campaign on election day itself in Pennsylvania has done him no good. Meanwhile, CNN projects that Republicans will retain hold of the US House of Representatives. Voters nationwide are voting for the House and the Senate tonight, and on a variety of social referendums as well.
21:20 Andrew Sullivan points out in his blog that, even with Florida and Virginia in the bag – both far from certain – Romney's path to 270 votes and the White House has been brutally narrowed by the loss of Pennsylvania and likely loss of New Hampshire, too.
21:27 Pennsylvania stays Democrat, while at Romney HQ you could hear a pin drop as Fox News hands Wisconsin, another swing state, to Obama, putting the incumbent in the lead for the first time in the election, with 158 votes against Romney's 153. Romney and Ryan become the first presidential ticket since Democrats George McGovern and Sargent Shriver (1972) to lose both their home states, Michigan and Wisconsin respectively. In Florida, meanwhile, you could barely insert a cigarette paper between these candidates: with 81 per cent of votes counted, only 636 votes separate them. "Florida is nuts!" squawks one pundit.
21:37 CBS calls New Hampshire for Obama. Bill Daley, Obama's chief of staff, says, "the President's good news is coming together faster than expected". John Cassidy, of The New Yorker, says: "Obama is rampaging through the Midwest and looking good in Florida. Seems headed for a big win."
21:39 Tammy Baldwin wins in Wisconsin to become the first declared lesbian in the Senate. Also in the chamber will be the first native-American woman to win a Senate seat.
21:49 The Republicans are losing heart but the Democrats at Obama HQ in Chicago are still holding their breath: Pennsylvania is in the bag, but the Big Three swing states, Ohio, Florida and Virginia, remain up in the air.
22:00 Polling places (as they are known) close in Iowa and Nevada.
22:02 Hold the front page: Romney wins…Utah! Cynical liberal media types jeer unfeelingly in Romney headquarters at the candidate's success in the citadel of Mormonism.
22:08 Todd Akin, the Republican who said that if a woman were genuinely raped, God would make sure she didn't become pregnant, has been rewarded with the loss of his Missouri senate seat.
22:11 Can anyone now doubt that American liberalism is on the comeback trail? Elizabeth Warren, "a fierce consumer advocate who galvanised liberals across the nation", avenges the Democrats' defeat in 2010 in the late Edward Kennedy's stronghold, Massachusetts.
22:22 Obama has a puny lead in Florida – 49.8 per cent against 49.4 per cent. But the walls are closing in on the Republican: Romney needs to reverse that lead and win Ohio to remain in the race. Romney has failed to capture a single state and it is killing his challenge.
22:42 Romney wins Montana, North Dakota, Arizona; Obama wins New Mexico.
22:44 Over at Democrat HQ in Chicago they are screening a video about the President's campaign, The Road to November 6, Obama yelling out, during one of his innumerable visits to the Buckeye State: "Ohio I still believe in you. And I need you to keep believing in me!" Inside the hall the crowd is rapt, every eye on the screen. Everyone keeps saying Obama is up in Ohio; if the President wins Ohio, it's all over. But no one's calling Ohio.
22:45 With 91 per cent of precincts counted in Florida, Obama's lead in the state narrows to 49.7 to 49.5.
22:46 Miles to go before we sleep: Obama 172 votes Romney 163.
23:01 Obama wins Washington state, California and Hawaii. No surprise there.
23:05 ABC claims that Jeb Bush, Dubya's brother and former Florida Governor, has told the Republican camp that it has lost Florida.
23:07 Obama 244 votes Romney 203.
The lead widens. Huffington Post: "THE WALLS ARE CLOSING IN ON ROMNEY."
23:14 Fox News – the Republicans' unofficial network – calls Ohio for Obama. Game over.
23:25 The networks agree on Obama's win in Ohio. BBC: Victory for Obama. Split screen shows the two camps: Obama's in Chicago, waving thousands of flags, swaying, cheering, chanting "four more years", a banner that reads We HAVE overcome ; Romney's over in Boston, glum, silent, hands in pockets or folded in chest, tears glinting.
23:29 An apparition from the past, Dubya's dreaded Svengali, Karl Rove, emerges from nowhere to berate Fox for declaring Ohio for Obama: plenty of votes still to be counted, he insists. Republicans cheer as the wonk of wonks demands a recount.
23:37 Romney reported en route to the silent, grim Boston ballroom where his hopes have expired. Meanwhile, Rove tries to persuade Fox's "decision desk" to "uncall" Ohio for Obama.
23:53 Romney and his running-mate Paul Ryan arrive at the ballroom.
00:17 Irrelevant results continue to stream in. Romney has yet to call Obama and concede defeat. He has no statutory obligation to do so, but it's the done thing. Speculation grows that Romney is either: a) writing that speech conceding defeat that he left unwritten before the polls closed; or b) joining Rove in demanding an Ohio recount.
00:43 If Romney has indeed been querying the Ohio result, it no longer matters: Virginia goes to Obama – 13 more electoral votes in the bag, and now he's out of reach.
00:55 Romney, smiling weirdly as if happy, concedes defeat, and brings on a large group of relatives to share the moment.
01:35 It's all over: Florida will carry on counting and squabbling for hours if not days; it may be as long or longer than that before the popular vote is known, though Obama is in with the chance of a decent win there, too.
But all that's now a sideshow. Forty minutes after Romney waved a final sad goodbye, Obama brings on his family to vast cheers in Chicago. "We rise and fall as one American family," he says. "That common bond is where we must begin."