Trace element analysis of obsidian allows us to identify the sources of artifacts made from this desirable tool stone. Most obsidian studies focus on material recovered from a single site the 260 obsidian artifacts in this study were recovered from 72 sites on the east side of the Mt. Hood National Forest. These were identified as originating from 18 known and 12 unknown sources. The known sources include major regional quarries, local sources and an unusual number of small sources located some distance away. The artifacts in this study were recovered from short-term seasonal (summer) camps and have a more complex distribution then that of near by winter settlements. The implications for identification of territorial boundaries (using the local sources), long and short distance trade, seasonal round, and site age are explored.