Room 31W is an original Chacoan room that was later subdivided into two smaller rooms: 31A (east half) and 31B (west half). Room 31W is located directly east of Room 30W in the northwest sector of Salmon Pueblo. The original Chacoan room measures 3.8 by 2.9 m. It lies south of and is connected to Room 43W by a sealed doorway. Room 31W contained 30 individual strata including Chacoan and San Juan floor complexes, roof-fall, structured trash, wall and wall-fill units, and feature-related strata. The Chacoan occupation floor in the room contained a number of large lithic core tools, faunal remains, and ceramics. The assemblage suggests that faunal processing and butchering took place in the room. Twenty-six features were identified in Room 31W including Chacoan doorways on the north and south, roofing-related features such as vigas, latillas, and other beams, two San Juan burials, several pits for storage and trash deposition, and two hearths. One burial was located beneath the San Juan occupational floor. The room was used for storage and as a trash zone during the Chacoan period. The first fire in the room probably happened around 1190–1210. The second fire was part of the closing event at the pueblo, in the mid 1280s.