Americans head to polls with historic election on a knife edge

With no clear swing-state advantage for Kamala Harris or Donald Trump, the US is poised for a long - and tense - wait for results

Election day has arrived in America, with tens of millions of voters set to head to the polls on Tuesday in one of the closest and most consequential contests in modern US history.

The Democrat Kamala Harris and her Republican opponent, Donald Trump, appear locked in a knife-edge contest with hardly any daylight between the pair in national opinion polls that have barely budged in weeks.