Knight-Swift can trace its origins back to 1966, when Swift Transportation was founded to transport steel and cotton between Los Angeles and Phoenix. The company grew over the following decades, until by 1990 it was a 125 million U.S. dollar carrier owning over 800 trucks. At this time Swift Transportation became a publicly listed company, and used the money raised to expand their operations by purchasing rival companies. By 2009, Swift reported revenue of 2.5 billion U.S. dollars and had operations across the United States, Canada and Mexico, although their size decreased following the 2008 recession.
Also in 1990, four cousins employed by Swift - two sets of brothers who shared the surname Knight – left to found their own freight trucking company, Knight Transportation. Originally starting with a small number of trucks transporting general goods between Los Angeles and Phoenix, the company’s revenue was around 13 million U.S dollars in 1991. By 2018, Knight Transportation had grown to report revenue of 5.34 billion U.S. dollars.
In 2017, Knight Transportation and Swift Transportation merged, to create the new company Knight-Swift Transportation Holdings. Each company still continues operating under their own brand as separate business segments, however, with the trucking segment of Swift-Truckload being the largest. The combined company had an operating fleet of 69,544 trailers and 19,156 tractors for 2018, and offers a range of dry van and refrigerated full truckload services, as well as rail intermodal and logistics services.