Room 100W is an original Chacoan room and one of the largest rooms in Salmon Pueblo. It is located in the northeastern section of the Pueblo and measures 6.4 x 6.4 m. Unlike many other rooms at the Pueblo, this room was not architecturally modified during the San Juan occupation. At least two Chacoan floors could be defined, which suggests multiple use functions. The original floor shows numerous pits, hearths, post holes, and a corrugated vessel set in the floor. The room was abandoned during Chacoan times and was subsequently used as a major Chacoan and Chacoan-San Juan transition trash repository. A total of 76 strata was found in 100W; most were Chacoan, but several San Juan deposits were encountered, including a roof-fall layer and a structured trash deposit. Below the San Juan deposits were a couple of mixed layers with Chacoan and San Juan sherds. Chacoan strata included structured trash deposits and feature related strata on top of a floor layer. This floor layer contained hundreds of artifacts. Thirty-eight features were associated with 100W, most of Chacoan origin. The two San Juan features were both burials interred late in the occupation. The Chacoan features comprised hearths, two macaw burials, two turkey burials, an ash pit, vent windows, niches, many floor pits, doorways, and one burial. The Chacoan features suggest a primary living function for the room while the San Juan burials and trash deposits indicate dumping refuse and interring the dead. Tree ring dates indicate initial construction around 1090. The strata and features indicate that 100W was continually used throughout the San Juan occupation, into the late 1200s.