It typically is urban vs. rural.
The other blue/red are college towns. Look at the map for WA state for an example. The Blue country in Eastern WA are Spokane and to the south is the county where Washington State is located.
The same in every other place where big universities are located around the country. Here in NH the bluest part of the state is where Dartmouth in located. The next bluest is where UNH is located.
“The other blue/red are college towns.”
That’s only because college kids know everything. At least until they have to pay their own way and take care of their own families.
I predict the following events that could well happen in part or whole in the next two to three years. I hope I am 100% Wrong. 1. We get into a shooting war with Russia. 2. The Polish/USA/UK war with Russia Belarus goes well for us at first. 2. It turns into WW II with two sets of nations at war—called in USA :The Allies vs the Axis. 3. Months of fighting and privation, rationing, the draft, millions dead.
4. We lose the war and face occupation, war crimes trials, and corruption exposed. 5. Civil War breaks out, with Red vs Blue States. 6. America is divided into two nations.