Kenworth Trucks, Inc., is an American manufacturer of medium and heavy-duty trucks based in Kirkland, Washington. Kenworth was founded in Seattle, Washington in 1912 by brothers George T. and Louis Gerlinger, Jr. as a car and truck dealership known as Gerlinger Motors. In 1914, they decided to build their own truck with a more powerful inline six-cylinder engine, the first put into a commercial truck.