When do they vote

Polls are open from 7 a.m. until 7 p.m. In South Carolina, you must have a valid photo identification to vote.

Who’s ahead in the polls 

Former Secretary of State Hillary Clinton has a wide lead in most all  polls from the state coming into the primary. According to RealClearPolitics, Clinton has 58.3 percent of the vote  compared to Vermont Sen. Bernie Sanders'  31.7 percent. Sanders cut Clinton's lead in half since a November 2015 poll showed Clinton ahead by 52.7 points.

Strengths for each candidate

For Clinton, the black vote accounts for a large part of her lead. African Americans made up 55 percent of the primary vote in the 2012 election and that trend looks to hold for this primary. For Sanders, he's ahead in the white vote. White voters favor Sanders 54 percent to 40 percent for Clinton.

The important question, how many delegates?

The primary is the last before a dozen states vote on Super Tuesday, March 1.