How can two cities, sometimes just miles apart, have completely different political views? Is it history, culture, economics, or something else? Where did these divides begin?

I'm not interested in arguing about which political party is right or wrong. I'm curious how communities develop such different political identities. Is it influenced by history, economics, education, religion, migration, or simply the environment people grow up in? And how much of what we believe politically comes from where we live?