Need information on radio broadcasting distances.?

FM is not a good chioce. Its in the VHF frequencies and has only "line of sight" coverage, meaning not much more than 50 mile radius. AM can cover much larger distances, especially at night when "the skip is in". Not unusual in California to hear Utah and Alaska at night. You need a big transmitter and a clear channel. The first is economics, the second is government. Sorry I don't have links to suppliers, but GE and Westinghouse come to mind for big transmitters.