Good news for political devotees hoping to get to bed early: Barring unexpected snags, we should know the results of the Republican primary in South Carolina well before midnight.

The polls will close at 7 p.m. Eastern time, and the state tends to count fast. When Democrats held their primary in the state on Feb. 3, results started coming in just a few minutes after the polls closed. The Associated Press was able to call the race for President Biden within 30 minutes.

Nobody on the Republican side is expected to win the overwhelming 96 percent that Mr. Biden won, of course. But even with the more competitive race between former President Donald J. Trump and Nikki Haley, it’s likely to be an early night.

By about 10:45 p.m. on Feb. 3, less than four hours after the polls closed, nearly all ballots had been counted.