In addition to the U.S. presidency, voters in several states were also deciding the fate of a number of state and local ballot issues in Tuesday's election.
Early returns show a ban on same-sex marriage has been overwhelmingly approved in Kentucky, Georgia, Ohio, Oklahoma, Mississippi, Michigan and Arkansas. The issue was also on the ballot in four other states.
In California, voters faced a proposal to fund embryonic stem cell research. It would authorize the state to sell $3 billion worth of bonds to fund the research.
An initiative in the western state of Colorado could affect this year's presidential election. The measure would split Colorado's nine electoral college votes according to the percentage of the popular vote won by each candidate -- rather than give the entire bloc of votes to the winner. If approved, it would have immediate effect.