First results are looking fragile with Hillary Clinton at 47.8 per cent of the vote in the key state of Florida.
Donald Trump has 49 per cent. He is currently more than 110,000 votes ahead.
Full results are yet to come in and around 95 per cent of the state's votes have been counted.
The winning candidate needs more than 270 electoral votes and Florida has a significant 29 votes up for grabs.
Its swing state status means it tends to have no significant support for either party, therefore a win for the Democrats or Republicans is a key victory and a good opportunity to win electoral votes.
It is one of 13 important swing states across the US.
In 2012, it was the last state to be called in the presidential election and was also the closest.
Tampa was the site of the Republican National Convention, but the state ultimately went to president Barack Obama with 50.01 per cent of the vote and 49.13 per cent to Republican Mitt Romney.
Florida is one of the first swing states to close its polls and release the results.
