Vote counting began late Thursday in an epic independence referendum that could break up the centuries-old United Kingdom and create Europe's newest state since the collapse of Yugoslavia.
After months when it looked like the independence camp could not win, a surge in support in the final two weeks has left pollsters warning the outcome is too close to call.
"I felt different today than most of the previous votes. I might be making a difference and my vote counts," 23-year-old Aidan Ford told AFP after he cast his ballot in favour of independence in Glasgow.
The campaign has fired up many Scots who have previously taken little interest in politics and has revolved around questions of national identity that are rarely discussed in Britain.
Queues of voters, some wearing traditional kilts and tartan hats, had snaked outside polling stations, and election officials expect turnout as high as 80 percent.
Polling officials in the fishing port of Fraserburgh said that an 80-year old woman had voted for the first time in her life.
Some 97 percent of eligible Scots -- nearly 4.3 million people -- have registered to vote, underscoring the passions that the historic decision has ignited across the nation.
The question for voters at Scotland's more than 5,000 polling stations was "Should Scotland be an independent country?" and they are asked to mark either "Yes" or "No".
In a survey of people after they voted, pollster YouGov predicted Scotland would reject independence by 54 percent compared to 46 percent in favour.
- 'Vote yes... for us' -
Some ballot boxes were to be flown by helicopter and others brought by boat from remote islands to be counted after polls closed, with the final result predicted to arrive in the early hours of Friday.
The closure of the airport on the Isle of Lewis due to fog meant ballot boxes would have to travel by fishing boat, potentially delaying the declaration of the Western Isles, according to BBC news.
At the counting centre in Scotland's oil city Aberdeen, boxes of postal votes were tipped out onto tables at the stroke of 10:00 pm when polls closed, and officials immediately began sorting the ballots.
International media descended on the Edinburgh venue where the city's ballots will be totted up to witness a count that could have repercussions from Spain to Canada.
The Scottish National Party has said it hopes for full independence by 2016 if it wins, and a range of separatist movements sent representatives to Scotland to learn from the election.
"Scots, please, vote yes, for yourselves, but also for us," Daniel Turp from the Parti Quebecois said at a press conference in Edinburgh where 29 European separatist movements also signed a declaration calling for self-determination.
Leaders of France and Spain warned that separatism risked undermining Europe in the run-up to the vote.
The mood in cities across Scotland was jubilant, with crowds draped in flags gathering to celebrate in Glasgow's central St. George Square and outside the parliament in Edinburgh.
"We are going to stay out till the result," said Dylan McDonald, 17, one of Scotland's 16- and 17-year-olds who have been able to vote in the referendum for the first time.
A palace spokesman told Sky news Queen Elizabeth II was following events from her family home Balmoral Castle in rural Scotland.
She is "kept abreast of information... from her team of advisers in London and Edinburgh," the spokesman said.
- 'Ripped out of the UK' -
British Prime Minister David Cameron has pleaded with Scots to vote in favour of keeping "our home" and has warned the break-up would be a "painful divorce" full of economic risks.
Many people in the rest of the United Kingdom are concerned about the prospect of Scottish independence, which would sever a deep bond and cut the UK's surface area by a third.
"At last the threat we have over Scotland's future may be lifted if people vote the right way," said pensioner Alistair Eastern, 60.
"We just have to hope that it turns out with the right result and Scotland isn't ripped out of the United Kingdom by the nationalists."
A "Yes" vote would not mean independence overnight but would trigger complex talks on how to separate two intertwined economies and eventually end a union dating back to 1707.
A lot of the debate has focussed on the economy, what currency an independent Scotland would use and whether it could be a member of the European Union.
Scotland's Parliament, opened in 1999, holds some powers devolved from Westminster to set policy in certain areas of domestic policy, such as health and education.
Cameron has promised to grant it sweeping new powers in the event of a "No" vote, but this will not be enough for some.
"I voted 'Yes' because I decided Scotland should be governed by itself," said university administrator Sarah Rowell, 36, in Edinburgh.