The pioneers and settlers of the Oregon Territory were not of one ilk. They came from various places and brought their separate speech patterns with them. This study sought to identify which major North American English dialect was present in the first half of the 20th century in Oregon. Analysis relied on the descriptions for the Southern, Northern, Midlands, and Western dialects. Some dialect features have acoustic measurements attached to their descriptions, and others do not. The analytical process was based on acoustic measurements for vowel classes and individual tokens, as well as global observations about the place of a particular class means within the larger vowel system. Findings indicate weak presence of Southern and Western speech patterns. The Northern and Midlands dialects were present, but they were not advanced. No single dialect predominated. Part of the process attempted to find a dialect diagnosis to help determine a one-step indicator as to which dialect may be present. Observations implied that the front/back relation of /e/ and /o/ is a reliable dialect indicator.