Pogo Stick Ride or Saddle Up Your Bucking Bronco

I too have noticed this on Wisconsin's highways... At one point it was making me so nauseous that I moved to the left-most lane, and all was well. I assumed the right hand lane(s) were more beat up.

I only have a single axle trailer and speed didn't much matter but faster was better as the frequency increased with speed. Noticed this first with my station wagon towing my trailer, and also a half ton truck towing the same trailer.