Philip Bump at WP:
Even as recently as 2000, four of the 10 most populous cities had Republican mayors. In recent years, that number has been zero.
That itself is a reflection of how the politics of place have shifted in the last two decades. Presidential election results show how urban areas have moved to the left — and rural areas much more sharply to the right. In 2000, large urban counties backed Democrat Al Gore by 18 points more than the national margin while rural counties backed George W. Bush by 15 points more. In 2020, that gap surged to 27 points in urban areas and 37 points in rural ones....
Why this shift? Well, consider another way of looking at the change in the leadership of America’s most populous cities: race and ethnicity.
A century ago, the mayors of America’s most populous cities were White men, uniformly. Slowly, that changed. Now, none of the leaders of the five most populous cities is a White man. In 2000, three still were....In 2021, The Washington Post published research considering why the gap between urban and rural areas was growing so wide. The conclusion? Views of race.
“Racial attitudes among all Americans best explain the gap in vote choices between rural and urban areas,” the authors wrote. “[T]he different rates of racism denial among rural and urban Americans appears to explain about three-quarters of the urban-rural gap in voting for Trump.”