Why are there so many cities and towns that are named after towns and cities in the US?

Question

Like Birmingham and Bristol

Answer 1

It's the other way around.

Answer 2

Lots were named by people who arrived in the middle of nowhere in particular, figured they'd better called the place something or other, and happened to come from places like Birmingham or Bristol.  In some cases, names were also selected to appeal to would-be immigrants from particular parts of Europe.

Answer 3

because people ran out of other names