Recent data from the Pew Research Center revealed that married men went from voting 62 percent for Donald J. Trump and 32 percent for Hillary Clinton in 2016, to 54 percent for Trump and 44 percent for Joseph R. Biden Jr. last year. That sizable shift — a 30-percentage-point margin sliced to 10 points, and a 12-point jump for the Democratic candidate — was underscored by the much lower movement Pew found among unmarried men, married women and unmarried women. Both the Cooperative Election Study and the Democratic data firm Catalist found smaller but still notable four-point shifts toward Mr. Biden among married men in the two-party vote share, or the total tally excluding votes for third-party candidates. “That’s definitely statistically significant,” said Brian Schaffner, a professor of political science at Tufts University who co-directs the Cooperative Election Study. “Married men are a pretty big group,” he added, “so that’s pretty meaningful in terms of the ultimate margin.” A partial explanation for this shift, and the simplest, is that the gender gap itself got smaller in 2020. Mr. Biden won 48 percent of men while Mrs. Clinton won 41 percent, according to Pew, even as female voters in aggregate hardly budged. Mr. Biden also improved on Mrs. Clinton’s margins among white voters; his movement among white married men was responsible for the shift among all married men, according to Catalist.