Room 51W is located in the central section of Salmon Pueblo. It is an original Chacoan room that was not structurally modified during the San Juan period. It measures 5.4 m x 3.2 m. Forty-five strata were identified in 51W. The upper strata are from the San Juan occupation of Salmon Pueblo and include two floor surfaces, two roof-fall layers, post-occupational fill, structured trash, and feature-related deposits. The six Chacoan strata are subfloor deposits, including wall foundations and artificial fill used for construction. Eleven features were identified in Room 51W. The Chacoan features included doorways in the north and south walls and the underlying foundation, whereas the San Juan era features consisted of two postholes. The function and use of the room is unclear. Based on the evidence, Room 51W was not heavily used in either period. Tree ring dates indicate construction in the initial Salmon construction phase at 1090. The room was continuously used throughout both occupations into the late 1200s.