Why Do Regional Stock Markets Exist?

Why do the small regional stock exchanges (e.g. Boston, Providence, San Francisco) still exist? It seems like trading on the NYSE or NASDAQ is pretty efficient and cheap-so why do firms trade on the smaller exchanges?
The last trades I had on the NYSE took all of a few minutes, I can’t imagine that a smaller exchange can be an efficient trading venue.
I would imagine that the regional exchanges were set up because local firms traded on them. But today, I don’t see this as a good reason anymore.

It’s a bit complicated.

Take a look at the Wikipedia entry for the Pacific Stock Exchange Just because you submit an order to buy 100 shares of a company listen on the NYSE, it does not necessarily mean that the order gets sent there. It can be routed to an ECN such as ARCA for execution.

is primarily an options trading exchange. It is owned by NASDAQ and trading is also done electronically.