Political leaders on both the sides have expressed confidence in the Scottish people, but uncertainty ripples below the surface.
In the short-term, British Prime Minister David Cameron would have most to lose if Scotland votes to leave the UK.
Some Conservative MPs believe he could even lose his job, according to The Independent.
Yet in the medium-term, a "Yes" verdict could have a much more dramatic impact on Labour than the Tories.
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Even a "No" vote would pose problems for Labour.
If Scottish MPs were excluded from voting on "English laws", as Tory MPs are already demanding, some Labour folk worry whether a Labour government would ever get a Budget approved by the House of Commons.
Whatever the result, British politics will change dramatically after the referendum.
Independence supporters today attended an event in the centre of Glasgow, where they were urged to "vote 'Yes' for a prosperous Scotland".
Opinion polls have failed to put either side decisively ahead. The latest polls indicated that the result remains too close to call and that the last-minute efforts were geared towards wooing undecided voters.
They all seem to suggest a lead for "No" at 52 per cent to 48 per cent for "Yes" to independence.
The turnout is expected to reach record levels tomorrow. More than 4.2 million people are registered to vote, 97 per cent of the eligible electorate.
The result is most likely to be between 06:30 BST and 07:30 BST, according to Elections Scotland.
Scotland is remote and sparsely populated in places, so some areas have to factor in geography and the weather.
Helicopters will be used to fly ballot boxes from islands in Argyll and Bute - where a third of its population live in settlements of fewer than 1,000 people - to the counting centre at Lochgilphead.