“Biden held onto much of the turf that Clinton won in 2016, but he also captured a lot of territory that Sanders carried four years ago. We found that much of Biden’s success can be explained by his dominance in areas with larger shares of white voters without a college degree….

The difference between Biden and Clinton’s performance is most obvious in areas with sizable shares of white voters who don’t have a college degree… the larger the share of a county’s population that is white without a college degree, the better Biden tended to perform compared to Clinton, even when Biden’s vote share in that particular county was smaller than Clinton’s.

Exit polls also underscore this trend, especially if we look at the race once the candidate field had winnowed after the February contests. In the 10 states that voted in March for which we have both 2016 and 2020 exit poll data,5 Sanders edged out Clinton among white voters without a college degree in 2016, 54 percent to 44 percent. But in 2020, Biden beat Sanders, 40 percent to 33 percent in those same states.

Even though we don’t have complete exit poll data from Michigan, the result there may best capture just how much ground Biden made up with white voters without a college degree, compared to Clinton’s performance with this group in 2016. Four years ago, Sanders won the state by about 1 point in a huge upset. He carried 73 of 83 counties while winning 57 percent of white voters without a college degree, per the 2016 exit poll. But in 2020, Biden won every county in Michigan en route to beating Sanders by nearly 17 points. The partial Michigan exit poll also found the former vice president won a majority of white voters without a college degree.”