Part of the problem with litter is there is no convenient place to dispose it. People dump tires, old mattresses, etc. along seldom traveled roads and other places because municipal dumping places are few and far as well as their charges for dumping are out of reach for many people. In some campgrounds, the "pack it in-pack it out" plan where you are supposed to take all your trash home with you, leaves people without any resource to discard leaky smelly trash they don't want in the passenger seat of their vehicle. Other campgrounds have one central spot for trash disposal, often quite a distance from the campsite.