The worst piece of highway that I can think of is highway 70 west of Indianapolis. The heavy truck traffic keeps the road in a state of disrepair. Their are so many heavy trucks that they own the highway. And what about these truckers who pull out to pass another truck and just ride along next to each other for miles at a time?
In St Louis, we have hiway 40 eastbound(it has been renamed to hiway 64 for god knows what reason) which passes over hi-way 70/55 in downtown St Louis but makes no connection to them. You have to drive through downtown city streets if you want to make the connection.