Because you had the LOCATION SERVICES activated on the device you were using... So, the GPS inside told the program where it was and the program picked the nearest Radio Station to display....
Maybe or maybe not but it does have an IP address, which locates one fairly closely in geographical sense...
This is cool! I can jump around from Detroit to Gaylord, zip across the country to Carson, and even visit Wagga Wagga... but I can't get the Far East Network from Okinawa.