Where can I find a statewide listing of fitness centers?

I am trying to find out which fitness centers are located where so that I will be able to decide on the best one for me. I was thinking that it might be nice to find a good fitness center part way through my hour long commute so that I can break up the commute a bit and exercise either on my way to or from work. Is there a statewide listing of fitness centers that I could check out so that I can find out what is available along the route I normally drive to work? That would make things so much easier.