It happens everywhere but the worst place I've seen so far is in Ca. on uphill sections of a highway with a passing lane. It's often a young driver in a small car. One of them nearly got squished last year when they passed us in a construction zone and came very close to rear-ending one of the construction trucks.
Seems like no matter how fast you go if you have an RV, they MUST pass you. Part of driving or towing an RV is always being vigilant and driving defensively no matter how right you are. I hate it when they tailgate you and you can't see them behind and then bam, they suddenly try and pass you out of nowhere.