Semi-trucks on American roads are often referred to with the "Tractor Trailer" moniker, which may be old-fashioned, but does reflect the truck's design.

There are about 2.8 million semitrucks (also called tractors) registered in the U.S. as of 2016. Their trailers—known as tractor-trailers—have no front wheels and can be used only when ...

Semi-trucks on American roads are often referred to with the "Tractor Trailer" moniker, which may be old-fashioned, but does reflect the truck's design.