g
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.