There used to be some ambiguity in the political aims of the parties, various Venn diagrams used to scoop up members of both parties. Not anymore.
I've got two reasons for you.
The culture wars and the 24 hour news cycle.
Divisive tactics that pulled ALL conservatives one way and ALL liberals the other.
It made us define ourselves and sort ourselves out. Brother against brother, friend against friend. Each year there were more wedge issues.
But little things like wars and threats of nuclear annihilation have ways of bringing people together. Just as in Ukraine right now where Jews are likely fighting alongside Nazis.
It's a wonderful world.
