Voters were deciding the fate of the controversial Amendment One - an amendment to the state constitution defining marriage as only between a man and a woman.
It puts North Carolina at the center of a growing debate between generations and America's major political parties over legalizing same-sex unions.
Amendment opponents have been drawing support from Democratic Party candidates, younger voters, urban areas and the NAACP, while supporters of the gay marriage amendment are finding their core support in the GOP, older voters, rural areas and conservative black churches.
Voters were also deciding who will be the Democratic candidate for North Carolina governor.
The latest polls taken before Tuesday showed the contest as a battle between Bob Etheridge and Lt. Gov. Walter Dalton. They led the rest of the candidates -- State Rep. Bill Faison, Bruce Blackmon, Gary Dunn and Gardenia Henley -- as the potential successor to Democratic Gov. Beverly Perdue and will likely fall rival to Republican Pat McCrory.
Libertarian Barbara Howe is already in the general election.
A runoff could be held if no candidate wins more than 40 percent of the vote.