In 1929, Locomotive #12 began work in Oregon's redwood forests for Hammond Lumber Company. Baldwin Locomotive Works manufactured and designed the locomotive as an articulated tanker, allowing it to make tighter turns than other locomotives. Southwest Lumber Mills purchased #12 in 1956, relocating it to Flagstaff. In 1959, the company removed its tanks and then in 1960, retired the locomotive due and donated it to Coconino County. The Arizona Historical Society (AHS) acquired Locomotive #12 in 1987. AHS purchased Caboose #99945 in 1988 from the Santa Fe Railroad and placed it near the locomotive, even though logging companies stopped using cabooses in 1920. The pair remained at the Fort Tuthill Fairgrounds until 1994, when AHS relocated them to their present location at the Pioneer Museum.