My university is in Oklahoma and most companies are in east coast and west coast in the US. I am a bit worried if a PhD will be worthy from an average university with poor location. Should I apply to a college where there is a bunch of industries around?
Far more important than location is the quality of the program. You can get some measure of the program's quality by looking at the job placement of recent graduates. If they are making it out to the companies you are interested in, then you should be fine. If all the graduates are staying in-state, you will probably want to look to a different program.