What road rules do I need to be aware of?

If you are pulled over by a cop in America, never exit the vehicle to talk to the cop. Wait patiently to be approached and told what to do. Also, don't be moving around and making suspicious moves like reaching under your seat or opening the glove compartment. Remember, many people are armed both legally and illegally with hand guns in this country and cops like to go home to their family at the end of the day. Don't take a cautious attitude as bad manners; safety first for them and you

EDIT- I just remembered to advise you that while many states have legalized marijuana both medically and recreationally when you are in a national park federal law still applies(they don't like marijuana and it's still federally illegal). I've seen a guy with a joint in his ashtray handcuffed and taken away and 5 kids outside the Maswik Food Court(cafeteria in Grand Canyon) handcuffed and arrested for smoking a joint.