Please notice the name change to this forum. It is not just for fast food joints. Never was actually but now the name is broader so that maybe we won't have so many arguments.
Well I deleted the earlier thread with this info because people were already starting to argue over such a simple thing.
If it has multiple locations, has a web site showing multiple locations, or offers corporate info, it's probably a chain. If you can go to one in NY or in Calif., it's probably a chain
If Mom and Pop and the kids each have one in a small geographical location, it probably isn't.