Knight Transportation was founded in 1990 by four cousins: brothers, Randy and Gary Knight and brothers Kevin and Keith Knight. The four cousins worked for Swift Transportation, also based in Phoenix, and Randy was even a part-owner in Swift when Jerry Moyes bought out his interest. The Moyes family and the Knight family both were raised in Plain City, Utah, before moving to Phoenix in the late 1960s. In 2017, Knight Transportation merged with Swift Transportation.

Knight began transporting general commodities from Phoenix, Arizona, to Los Angeles, California. Starting with just a handful of trucks and one service center in Phoenix, Arizona, the company now runs a fleet of over 4,000 tractors and more than 8,700 trailers (dry, refrigerated, and brokerage). Revenues have grown from over 13 million in 1991 to over $866 million in 2011, with operating ratios at or near 80% year after year. They have grown from a few associates to more than 4,000, and from a family-owned business to a publicly held company trading on the New York Stock Exchange (KNX) in 1994.

Knight engages in the transportation of general commodities in the United States. It provides asset-based dry van truckload and temperature controlled truckload carrier services primarily to short to medium lengths of haul. The company also offers non-asset-based brokerage services. As of September 24, 2007, the company operates 27 regional dry van service centers, 6 regional temperature controlled service centers, 12 brokerage service centers, and 13 truck and trailer sales locations.

According to wikipedia