Mr. Biden has been criticized recently for having opposed busing in the mid-1970s. At the time, Democratic-leaning voters opposed busing by 79 percent to 21 percent, according to the General Social Survey. Over all, it was about as popular with Democratic voters as the Trump tax cuts are today.

White voters without a degree were still a majority of the party’s voters in the early 1990s, when Democrats were seeking to co-opt Republican messages on welfare and tough-on-crime policies . By then, the share of Democrats who believed that whites had a right to segregate neighborhoods had dropped to 15 percent, from 40 percent in 1972. But 15 percent is still a significant share, about as large a share as Hispanics represent today in the party. Self-identified moderate and conservative Democrats outnumbered liberals by two to one.

A Pew Research report from 1994 offers a striking look at the Democratic coalition at that time. It was an early edition of Pew’s running political typology series, and it included four Democratic-leaning groups under the headline “The ‘Not So’ Left.” Some groups were characterized as “socially intolerant,” or as holding “strongly conservative views on race and social welfare programs.” Even “New Democrats” rejected liberal views on race.

Today, self-identified liberals equal or even outnumber the combination of moderates and conservatives within the party. White voters without a degree represent just 30 percent of Democratic-leaning voters, according to an Upshot analysis of Pew Research surveys from December 2017 to September 2018. Pew’s typology now includes an ideologically consistent, liberal group.

There is no doubt that this is not the Democratic Party of the early 1990s. But it is not the Democratic Party of “woke” social media either. It is somewhere in between.

Mr. Biden, for instance, recently faced criticism after accusations that he touched some women in ways that made them feel uncomfortable. It was a crisis for his bid, or at least it seemed that way if you closely followed news reports or were active on social media. But a recent Fox News poll found that just 15 percent of Democrats said they were “very” or “extremely” concerned about the criticisms, while 51 percent said they weren’t concerned at all.