As the “First in the South” primary, South Carolina presents one of the most significant early challenges for presidential hopefuls. On the Republican side, the Palmetto State is seen as a firewall that can solidify establishment campaigns and break the momentum of insurgents who gained traction in New Hampshire and Iowa. On the Democratic side, South Carolina importantly tests a candidate’s appeal with African American voters, usually a key liberal demographic.

Here’s what you need to know about the dynamics of this primary, from voting patterns to the history of dirty campaign tricks.

The insurgent killer: Republicans in South Carolina

While Iowa and New Hampshire are known for giving insurgent campaigns a big break, South Carolina is better known for breaking insurgent momentum. Establishment candidates often pull away in this state before going on to win the nomination. In fact, the winner of the South Carolina Republican primary has gone on to win the party nomination in every election cycle that South Carolina has held a primary with the exception of 2012, when Newt Gingrich secured victory.

Part of the reason why South Carolina is such a good test is that it is home to two key but often dissimilar blocks of Republican constituencies: evangelical Christians and political moderates. If candidates can find success with these groups, that’s often a strong signal that they are road-tested for the larger nomination battle.

Democrats and the South Carolina Primary

South Carolina enjoys a greater general importance on the GOP side, but it does provide a crucial benchmark for minority voting on the left. Democrats have traditionally done well within the African American community, and roughly 28% of Palmetto State residents are black or African-American (including 9 counties with a black population of at least 50% or more). Because Iowa and New Hampshire are overwhelmingly white, South Carolina is the first real gauge of how Democratic candidates will appeal to African-Americans.

The Wild Wild South

Both Iowa and New Hampshire are famous for fostering a unique brand of retail politics. Candidates do well by shaking hands, hosting intimate town halls, and even dining with voters. The South Carolina primary, on the other hand, has earned a reputation as a place where political operatives seek to make mischief.

One of the most infamous of these instances occurred during the inaugural 1980 Republican primary: Lee Atwater, a key adviser to the Ronald Reagan campaign, met with a group of black ministers and told them his campaign was “broke,” and that funds could not be freed up for much-needed voter registration services. He advised the ministers to speak to contender John Connally’s campaign in regards to voter registration funding. Immediately after the meeting, Atwater phoned a third Republican campaign, that of George H.W. Bush, and notified them of Connally’s attempts to “purchase” the Black vote. This move pitted Connally and Bush against each other over public allegations of buying minority votes, all while Reagan steered clear of the sticky controversy. Connally went on to spend $10 million dollars in the state, only to come away with one delegate.

Things haven’t improved in recent years. In 2000, voters received anonymous phone calls asking if they would be “more likely or less likely to vote for John McCain for president if [they] knew he had fathered an illegitimate black child” – a shamefully misleading question. In the 2008 primary, fake Christmas cards claiming to be from the Romney family with controversial quotes from the Book of Mormon were sent to registered Republicans around the holiday season. An already volatile campaign season in 2016 could result in even more questionable tactics being used in the state.

Historical South Carolina Primary Results 

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This year, the Republican primary will be held on February 20th, while the Democratic Party is scheduled for February 27th.