Is it racism or classism? It appears almost like rural (small towns) versus urban (Cities) split. And those votes are kenyan like 80% for trump in rural America; and 20% for Biden; and in the cities the reverse is true.
The map has never really changed - coastal populous cities on edge of the country - both east and west coast - support democrats - always blue
The middle large swathe of America solidly republican - always red.
But as long as there is good balance - it's no biggie. 4yrs for rural America. 4 yrs for urban America. Republican and Democrat make for good PING PONG. We need the same in kenya - 5yrs for Kalenjin; 5yr for kikuyu 
or we can spice it up - GEMA versus Non-GEMA ping-pong
It's not really racism like you have in Kenya - because in kenya - whether in Kisumu or Malindi or Pokot - a Luo or Kikiyu or kalenjin will vote certain way.
There are millions of whites - in cities - who don't subscribe to this racism. It more a rural America thing.
Urban America is all nice and cosmopolitan. Rural America remain white and mostly backward. And thanks to gun ownership - it's pretty closed scary place for non-whites generally.
In a very broad sense, there is an urban/rural divide. But there aren't enough people in the rural areas to match the cities. That mass of red you see in red/blue electoral college maps is mostly just empty land. The farms are huge. The reality is more like a blue urban core, a purple suburban area, and red as you radiate further out.
Outside of a handful of states like New Jersey and Massachusetts, most states are purple. Blue around urban areas and reddening as you move further out. So even in a red state like Arkansas, you will have deep blue around Little Rock, and red as you radiate out. Generally the more diverse an area is, the bluer it is.
As an example, to win statewide in Illinois, you just need to win Cook County(almost half the state population) and then remain competitive(even if losing) everywhere else. The suburbs around Cook County also lean blue. The rest of the state is deep red with blue holdouts in Champagne, Springfield, East St. Louis etc. It's a pattern across many states with big cities.
As for racism, it's part of America's culture. In my experience, you can find it anywhere. Of course in bigger cities, there is less social license for the blatant variety - so people are conditioned to abhor it. It doesn't mean it's not there. But at least it's not tolerated.
Granted, one party has made peace with it(arguably made it a cornerstone), and the other has made a point to fight it. Demographic change is at the heart of the current turmoil in American politics.
