You said cold weather makes it worse--which might explain why there are high numbers in North Dakota, South Dakota, Wyoming, etc. We've had a really cold start to late fall and early winter here. You didn't mention Minnesota--which has had much harsher rules than neighboring states--yet is experiencing the same rise in positive tests. The virus seems to make it's way through the country, hitting certain regions, before moving on. It hit the northeast early, then the Sun Belt states, etc.
Also, North Dakota may be rural, but almost half of the state's residents live in the two largest metro areas in the state (Bismarck and Fargo). No state is all that rural anymore--especially since there aren't nearly as many small family farms as there used to be. The state may be desolate, but the people that live here are concentrated--just like most states--so I think that argument is mostly overrated.
