Riding the strength of her support among African-Americans to a resounding victory in the Palmetto State, Clinton seized the momentum in the Democratic presidential race -- winning her third of four early-state contests just three days before the race goes national on Super Tuesday.
It was a bumpy ride through the early states -- but Clinton's firewall of minority support held, helping her seal a close contest in Nevada and then turn South Carolina into her first dominant win of the 2016 race. Headed into Super Tuesday, the confidence Clinton's campaign had after October and November is back.
"Tomorrow, this campaign goes national," Clinton said in her victory speech. "We are going to compete for every vote in every state. We are not taking anything and we are not taking anyone for granted."
The South Carolina win is especially important because of what it means for the 11 Democratic contests that are on tap for Tuesday.
Clinton is eyeing six Southern states with heavy minority populations as a way to lock in a clear delegate advantage. She's hoping for big wins in Texas, Georgia, Virginia, Tennessee, Alabama and Arkansas.
Sanders, meanwhile, has his home state of Vermont locked in, and he's hoping for wins in Colorado, Minnesota, Massachusetts and Oklahoma.
Clinton's South Carolina blowout effectively guarantees that Sanders will have to scrap for those states -- and would struggle to expand his playing field, leaving Clinton's six targets intact.
Clinton's minority support
South Carolina's electorate climbed from 55% African-American in 2008 to 62% in 2016. And the vast majority of those voters -- 84% -- backed Clinton, according to exit polls.
The former secretary of state isn't messing around in courting black voters: She had Morgan Freeman narrate campaign ads. She had strong allies like South Carolina Democratic Rep. Jim Clyburn on her side. She has leaned hard into her alliance with the White House, saying Saturday night she wants to "build on the record and accomplishments of President Obama." She has contrasted sharply with Sanders on issues like gun control and portrayed him as a one-note candidate concerned only about income inequality.
To underscore her support on issues important to African-Americans, Clinton highlighted the role that five mothers of black victims of gun violence who campaigned alongside her in South Carolina.
"They all lost children, which is almost unimaginable. Yet they have not been broken or embittered. Instead, they have channeled their sorrow into a strategy and their mourning into a movement," she said.
Two more important exit poll findings: Most voters say race relations haven't improved in recent years -- and very few Democratic voters trust Sanders more than Clinton on race-related issues.
Sanders' not-quite revolution
It's not like Sanders woke up Saturday morning expecting a win.
He practically conceded the state on the eve of the Nevada contest by declaring it was "on to Super Tuesday." He spent the day in Texas and Minnesota instead. He didn't even plan a speech after the results were announced.
But perception isn't quite reality: Sanders' investment in South Carolina reveals a campaign that was hopeful his message of tackling economic inequality and reforming the criminal justice system would both make the state competitive and show he could win minority voters in other Democratic primaries.
He invested $2 million in advertisements, some featuring Spike Lee. His campaign had nearly 200 staffers in the state. And he opened 11 South Carolina offices.
The results revealed two big problems for Sanders. One is that he hasn't made the inroads he'd hoped for among African-American voters. Almost as significantly, he couldn't turn out the young voters age 18-29 who are the single strongest constituency of his campaign. Those voters made up just 13% of South Carolina's electorate, according to early exit polls, after comprising about one-in-five in other early-voting states. Disinterest among young voters is a particularly troubling sign.
Sanders, however, kept the race close among white voters, losing just 53% to 47%. And he won two in five voters age 44 and under -- not good, but better than the one in five he won age 45 and older. It's a signal he can still rack up large shares of delegates in whiter northern states -- and states where independents can participate in the Democratic contest, allowing him to bring new voters into the electorate.
Speaking in Minnesota Saturday night, he tried to energize his supporters: "Football is a spectator sport. Democracy is not a spectator sport. Every person in this room is extremely powerful if you choose to use your power."
Clinton wins among whites, but struggles with men
Clinton even Sanders out among white voters. While Sanders won white men 56% to 44%, Clinton won white women 60% to 40%. She won whites overall, 54% to 46% -- a much smaller margin than her overall victory, but still significant, since Sanders typically outperforms Clinton with white voters.
Beyond the Democratic primary, Trump, like Sanders, dominates among white men. Clinton won't need to win those voters to win the election. But she can't be blown out, either.
While Clinton is bashing Trump on the campaign trail, she won't be able to start reaching out to moderate voters any time soon, with Sanders' strength among liberals constantly pulling Clinton leftward on policy.
"We don't need to make America great again -- America has never stopped being great," Clinton said, taking a shot at Trump. "But we do need to make America whole again. Instead of building walls, we need to be tearing down barriers. We need to show by everything we do that we really are in this together."
There was good news for Clinton, whose numbers on trust and credibility have lagged far behind Sanders in earlier contests. In South Carolina, 74% of primary voters said they consider Clinton honest and trustworthy -- better than Sanders' 63%.
Asked who is honest and trustworthy, 28% of primary voters said only Clinton. Another 17% said only Sanders. And 46% said both.
Bill Clinton's redemption
It was just eight years ago that Bill Clinton turned into a toxic asset.
The most naturally gifted politician of his generation couldn't keep it from getting personal in South Carolina, when he opened racial fault lines in an effort to diminish Barack Obama's threat to his wife's presidential bid. Obama won the state by 28 points.
All appears to be forgiven.
Bill Clinton campaigned across the state for his wife, allowing the Clinton campaign to capitalize on the sort of surrogate Sanders could never possibly match.
It was the latest sign that, despite his low-key role in the campaign thus far, the former President is finding a way to shed the baggage of his at-times damaging 2008 role and prove he remains a useful campaign asset.
Much of it has to do with Obama. Bill Clinton's "explainer-in-chief" 2012 Democratic National Convention healed most wounds that remained, and Hillary Clinton sealed the deal by positioning herself as the logical heir to Obama's policies-- with 70% of those who voted Saturday saying they want the next president to continue those policies.
Perhaps the best evidence that all is forgiven: In 2008, Clyburn, who'd endorsed Obama, was furious after Bill Clinton had called him a "bastard" in a late-night, post-primary phone call that Clyburn detailed in his memoir. On Saturday night, Hillary Clinton was introduced in South Carolina for her victory speech by Clyburn -- who was smiling and dancing on stage.