Voters must make their choice for president separate from the straight-ticket option.
In nearly all states that allow voters to choose all of the candidates from a political party, the so-called straight-ticket option includes the presidential race.
But in 1967, Democratic legislators in North Carolina — fearful of a down-ballot drag from presidential candidate Hubert Humphrey — decided to cut the presidential selection loose from other partisan races.
North Carolina is the only state with such a law. Only 17 states allow straight-ticket voting, while five other states have ended the practice in recent years, according to the National Conference of State Legislatures.
Political scientists say that every election year tens of thousands of North Carolinians fail to vote for president.
Although undervoting does not make a difference when the winning candidate's margin is substantial, it can be enough to potentially throw a closer election.
According to a Duke University study, about 1 percent of voters mistakenly failed to vote for president in 1992, a year in which President George H.W. Bush won the state by less than 1 percent.
An analysis by Duke graduate student Justin Moore found that 3.15 percent of voters didn't vote for president in 2000 and 2.57 percent didn't vote in 2004. The national election-year average is 1.1 percent.
In 2008, state Democrats sent mailers and ran other efforts to teach voters about the tricky ballot.
