Experts say there are a number of reasons for it.
Crowded highways cause tailgating and near-collisions, they say.
Another reason is the great urgency Americans have to reach their destination fast. CNN's Kathleen Koch reports 2 min. But a third, they say, is a combination of ignorance and bad manners. Second, people seem to be under more pressure, under more stress. But many who are rude on the road simply ignore traffic rules, or have forgotten them, or never learned them at all.