How good are American roads?

> Interestingly, I expected cold places to have lower road quality in general due to things like freeze-thaw cycles and the impact of road salting, but there doesn’t seem to be much correlation. Plenty of cold places (North Dakota, Wyoming, Minnesota) have good-quality roads

Not sure about those states in particular, but I have anecdotally noticed that some of the places with the harshest winters do some of the least road salting -- because salt is mostly usable for light to moderate snowfall and the people who live in the harshest climates are often better equipped to drive on hard packed snow.