This observation comes from all the way back when we first arrived in Idaho. I noticed this on some highways but until recently couldn’t figure out what it could be. Take a look at the grooves in the pavement in this picture (click it to enlarge).
What could cause these grooves? The concrete on the highway wasn’t driven on when wet or of lower quality than I’m used to. No, this is a result of studded snow tires wearing away the pavement. Studs and chains are legal and sometimes chains are required if you plan on driving out into the mountains. In Illinois there aren’t any real hills to climb and therefore studs are almost unheard of. And chains? Most folks from Illinois don’t even know what they look like much less how to put them on.