The results so far show that Mr. Sanders has prevailed by broadening his appeal among traditional Democratic voters, not by fundamentally transforming the electorate.
In Iowa, for instance, turnout for the caucuses was lower than expected, up 3 percent compared with 2016, and the increase was concentrated in more well-educated areas where Mr. Sanders struggled, according to a New York Times analysis; in the Iowa precincts where Mr. Sanders won, turnout increased by only 1 percentage point.
There was no sign of a Sanders voter surge in New Hampshire either, nor on Saturday in Nevada, where the nearly final results indicated that turnout would finish above 2016 but well short of 2008 levels, despite a decade of population growth and a new early voting option that attracted some 75,000 voters. The low numbers are all the more striking given the huge turnout in the 2018 midterm elections, which was the highest in a century.
There was also no clear evidence across the early states of much greater participation by young people, a typically low-turnout group that makes up a core part of Mr. Sanders’s base and that he has long said he can motivate to get out to the polls.