the roads in and around the cleveland metro area have high traffic loads; undergo long periods of fluctuating cold temperatures during the winter; and get nailed periodically by lake-effect snow and ice.

as such, they experience lots of freezing and thawing, experience high traffic from lots of tractor trailers and snow plows, and get coated with de-icing materials (salt, or more recently sand-based grit in some areas). synergistically, these conditions are extremely rough on paved roads, so potholes are ubiquitous and painful.

Another commentor explained how potholes form, but I'll add that Cleveland doesn't have a lot of money and tends to defer maintenance.

When I was living there, road signs saying "Steel Plate on Road" were a common sight. I remember the city fixed a water pipe and instead of re-paving the street, they just left several giant 4ft x 8ft steel plates with corresponding sign for over a year.

This is also true for the rest of the areas around Lake Erie, western PA, and probably western NY (I don't have much experience with that area).

I live about an hour south of Erie, PA and the road I travel to and from work has needed resurfaced after every winter over the last 3 or 4 years.

Case Western Reserve University has a good engineering program.