There are 8.22 million single-unit trucks registered in the United States, which travel more than 110.7 billion miles each year. Although single-unit trucks comprise three percent of registered motor vehicles and four percent of miles traveled, they are involved in nine percent of fatalities among passenger vehicle occupants in multivehicle crashes. Crashes involving single-unit trucks and passenger vehicles pose a hazard to passenger vehicle occupants due to the differences in weight, bumper height, and vehicle stiffness.