Fargo's growth is accelerating, and is already higher than williston/watford by a considerable margin. Most importantly, it's not dependent on commodity prices. FM has a 200,000 person lead, even if you hold it's population constant, you would have to add 15,000 people a year to the williston/watford area. Fargo's growth might be pushing 10,000 people a year, right now. (6700 last census estimate) We'll see when the next batch of census estimates comes out in the spring.