The idea of Joe Biden as a depolarizing figure, someone who aimed to transcend rather than exacerbate the nation's political divisions, was both a dominant rhetorical theme of his campaign and a major strategic premise behind his nomination. In particular, Biden was supposed to be uniquely appealing to the type of white, older, modestly-educated, socially traditionalist voter who had wandered away from the Democratic Party sometime between Barack Obama's first victory and Hillary Clinton's last defeat. A candidate who won back a significant share of this electoral bloc while receiving the energized support of the groups alienated by Trumpism—cultural liberals, metropolitan professionals, young people—would be in excellent position to gain the kind of decisive national victory that many polls suggested Biden would achieve.
In the end, that didn't happen. Whatever demographic and stylistic differences distinguished Biden from Clinton or Obama failed to change enough votes to reorder the fundamental electoral constituencies of both major parties. The geographic polarization that has defined 21st century American politics remains fully intact—but a few incremental improvements in Democratic performance turned out to be just strong enough, and well-located enough, to eke out an electoral college majority.
Most states continue to be faithfully Democratic or Republican in presidential elections. By 2016, statewide popular margins had grown to differ with the national popular vote by an average of 20 percentage points, meaning that an election in which the candidates split the national vote 50-50 would produce a typical state margin that was a 60-40 landslide for one side or the other. Biden didn't succeed in healing this particular national divide, as the average state margin remained at 20 percent in 2020: