Americans are heading to the polls to choose a new president after one of the most rancorous election campaigns the country has seen.
Voting gets under way in earnest on the East Coast from 06:00 EST (11:00 GMT), though some villages in New Hampshire have already polled.
Hillary Clinton and Donald Trump criss-crossed America in a hectic last-minute campaign push for votes.
Results should begin emerging late on Tuesday night, US time, from 04:00 GMT.
Both candidates have held rallies in the battleground states of North Carolina, Pennsylvania and Michigan.
Mrs Clinton urged voters to back a “hopeful, inclusive, big-hearted America” while Mr Trump told supporters they had a “magnificent chance to beat the corrupt system”.
Polls give Democrat Mrs Clinton a four-point lead over Republican Mr Trump.
A record number of Americans – more than 46 million – have voted early by post or at polling stations.
There are signs of a high turnout among Hispanic voters, which is believed to favour Mrs Clinton.