Romney campaigns in Ohio
Republican presidential candidate Mitt Romney has been campaigning in a fast-food restaurant in Ohio and told supporters "we are about to change America".
Tens of millions of Americans are voting to decide whether to re-elect Democratic President Barack Obama or hand the job to Mr Romney.
Polls will start closing in eastern states at 18:00 EST (23:00 GMT) and a winner could become clear within hours.
For in depth coverage as the US goes to the polls: BBC US election special report
- From the section US & Canada