In 2016, 206 counties that had voted twice for President Obama backed Trump over Democratic nominee Hillary Clinton. This year, Trump won 176 of those same counties, while President-elect Joe Biden won 20 of them; eight counties in Maine and two in Illinois are still counting votes, though Trump is almost certain to prevail in each.
The results show a microcosm of national trends that increasingly describe an electorate divided along urban and rural lines, and between voters of differing education levels.
The counties that stayed with Trump are largely rural, in many cases ancestrally Democratic areas that had not voted for a Republican presidential contender in decades. Those that swung back to Biden were more diverse and located closer to large metropolitan areas.
In Iowa, all 33 pivot counties that voted twice for Obama have now voted twice for Trump. Those counties are concentrated in the eastern half of the state, once the bastion of union Democrats.