What are the top rivalry between US cities?

LA and phx, ny and boston, ny and LA...tell me what you think are the biggest rivalries between any US cities...can be when i comes to sports, population, size, anything

Public Comments

1. Ann Arbor Michigan vs. Columbus Ohio Go Buckeyes!!!!
2. i guess NY
3. Philadelphia thinks its rival city is New York, although New York and Boston consider themselves rivals. New York and LA only are rivals in entertainment. Most rivalries have their basis in sports.
4. In the NFL - Cleveland (OH) Browns vs Cincinnati (OH) Bengals