As American started to vote in the presidential election, Democratic party candidate Hillary Clinton is in a much stronger electoral position than Donald Trump, according to CNN’s latest poll.

The TV channel said Clinton would only need to win one of the remaining battleground states to get to 270 electoral college votes and secure the presidency. Trump needs to win all of them.

Clinton is four points clear of Trump on 46 per cent to his 42 per cent in the popular vote, according to the latest CNN Poll of Polls, which averages results for the seven most recent publicly released national polls that meet CNN's standards, the channel said.

In a battle that focussed largely on the character of the candidates, Clinton and Trump made their final appeals to supporters late on Monday to turn out to vote.

If Clinton wins she will become the first US woman president. She spent eight years in the White House as the first lady in the 1990s.

A Reuters/Ipsos States of the Nation poll gave Clinton a 90 percent chance of defeating Trump and said she was on track to win 303 Electoral College votes out of 270 needed, to Trump's 235.