Once a long time ago I was driving my car and not pulling anything. I was doing 65 and the speed limit was 65. I had a string of cars behind me. Don't remember how many but I would guess something like 10. A cop coming from the opposite direction made a U turn and came after me. He said anytime you have 3 or more vehicles behind you you must pull over and let those vehicles pass. This was in Indiana and he said it tells you on the first page of the driving manual. I told him I was doing the speed limit and he said it didn't matter he could write me a ticket if he wanted to.