Power King tractors were built by Engineering Products Company (EPCO) of Wisconsin. Originally the name for certain EPCO tractors, Power King became the brand for the entire line in 1977. Power King was sold to Support Services International in 1990 and production moved from Waukesha to Beaver Dam. Production continued until the late 1990s when Power King was sold again. Eventually the Power King assets were sold to Yazoo-Kees and production ended. Mission Manufacturing now owns the rights to Power King and supports the tractors.