If there had been any doubt about whether the Republican presidential primary was heading toward an early conclusion, it was put to rest Saturday night by the voters of South Carolina.

With nearly all the vote counted, Donald J. Trump defeated Nikki Haley, 60 percent to 39 percent.

It’s not a staggering landslide. In fact, Mr. Trump slightly underperformed the final polls, thanks to a vigorous turnout for Ms. Haley in Democratic-leaning metropolitan areas. Her strength may even be attributable to voters who intend to back President Biden in the general election, as anyone could vote in the South Carolina primary, regardless of party.

But this isn’t just any South Carolina primary: This is Ms. Haley’s home state. Even losing candidates have usually managed to win their home states. Ted Cruz and John Kasich did so against Mr. Trump in 2016. John McCain (2000), Howard Dean (2004), John Edwards (2004), Wesley Clark (2004), Newt Gingrich (2012) and others all pulled off home state wins. For many of these candidates, their home state win was their only win. On Saturday, Ms. Haley didn’t come close.

A decisive home-state loss says everything you need to know (and you probably knew already). It confirms that she trails Mr. Trump by a huge margin nationwide — the kind of margin that made a home state win impossible. It throws cold water on any notion that greater name recognition would overcome her deficit in the polls. And it deprived her of the last, best chance to claim even a hint of momentum ahead of Super Tuesday, when nearly half of the delegates to the Republican convention will be awarded.

As a consequence, this race is poised to come to an end — and soon. Oddly, it’s not the final vote count in South Carolina that explains why the race might end so quickly. It’s the delegate count: Trump 44, Haley 0, with six more still uncalled.

You read that right: Mr. Trump won nearly all of the delegates from South Carolina with just 60 percent of the vote. That’s because Republican primary rules allow states to award most or even all of their delegates to the winner, and in South Carolina he was able to win nearly every delegate by winning the state and five of its seven congressional districts — with the final two still outstanding at this hour (to my eye, it looks as if Mr. Trump and Ms. Haley will each win one, yielding a 3-3 split among those six outstanding delegates).

There will be plenty more opportunities for Mr. Trump to win all or nearly all of the delegates of a state. California is one of those opportunities. Anything over 50 percent of the vote would give him every one of the state’s 169 delegates. Not every state has rules so favorable toward the winner, but with Mr. Trump faring so well nationwide — he leads the polling by around 60 percentage points — no set of rules would preclude Mr. Trump from obtaining the preponderance of the available delegates.

Together, Mr. Trump could easily win more than 90 percent of the delegates at stake on Super Tuesday on March 5, when nearly half of all delegates to the Republican convention will be awarded. That would put him just a hair short of winning the nomination and poised to clinch the nomination over the following week or two — before his first criminal trial, in New York, is set to begin.