Ever since 1980, when Ronald Reagan won the first South Carolina Republican primary, every GOP candidate who has won in this Southern state of fewer than 5 million people has gone on to win the Republican presidential nomination. State party officials are fond of saying the road to the White House passes straight through South Carolina.
South Carolina is a different battleground from the corn fields of Iowa and predominantly white New Hampshire. The state is poorer, more conservative and has a population that is 28 percent black.
Voters don't register by parties so Democrats and independents enter the mix in the primary.