The more obvious reason is that colder places do not get as many freeze-thaw cycles. It simply stays frozen for a few months. In contrast, much of the northeast experiences many more freeze-thaw cycles since even in the winter it is warm enough to thaw the ice on some days.

> 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

Salt isn't effective when it gets really cold so it tends to be applied more around freezing as opposed to below. It also depends on the road surface temperature as well, heat of the sun melts off snow and that freezes at night. So you'll find salt has to be applied intelligently to the conditions, on bridges for example, which I suppose would come from experience.

I also observe southern states seem to use more rubber instead of rock in their road surface. So that might be a factor on how robust they are to wear.

Yep, in New York the pothole season is early Spring rather than winter, for example.

This is somewhat true where I’m at in Canada. In the city, half the people have proper winter tires, the other half “wing it” with whatever they can afford/put-up-with.

Regularly see accidents all winter long from goofs sliding straight across multiple lanes of traffic or going off into the ditch. Only some of us are prepared.

We don’t salt, only drop sand grit and gravel sparingly. Our roads become ice rinks or snow piles for a decent portion of the winter.

Your comment about us being “better equipped” made me chuckle as I spent this morning watching my neighbours play slip-and-slide in the cul-de-sac cause they opted to not put their winter tires on.

As someone who grew up in the mountains, their behaviour is downright dangerous in my opinion.

> ... because salt is mostly usable for light to moderate snowfall and ...

Perhaps more important - salt's effectiveness fades as the temperature decreases. Sand and gravel do not have that problem. So if you're running the Road Dept. in an area where serious cold ain't some rare event - why would you bother with salt?

EDIT: I know the "melt to pavement, solar heating finishes the job" tactic. Which can work with heavier snowfall, if you plow/shovel before salting. Colder weather inhibits both halves of the melt-&-heat. (Plus the further north you are, the shorter & slantier the sun's rays get, even on clear days.)

I've often heard the cold climate given as the reason for the terrible roads in Quebec, but you clearly notice the roads getting better as you cross the border out of Quebec into Ontario for example.

Also depends on where you're looking. Cities will have worse roads because they're always digging working on gas and water lines, some of which leak. That disturbance of the ground will make things a lot worse than some rural road where the ground hasn't been disturbed since it was created.