This dissertation presents a dialectological study of the city of Erie, Pennsylvania, and the neighboring towns in the boundary area between the North and Midland dialect regions. Erie occupies a unique place in the dialect geography of North America, in that it appears to have switched status from the North to the Midland. Since the dialect boundary between the North and the Midland has remained stable throughout the rest of North America, this switch presents an intriguing test case for theories of dialect change and phonological structure. The field work conducted for this dissertation consists of interviews, word lists, minimal pair tests, and grammatical acceptability judgments. In addition, archival data was used to push the time depth of the analysis further back. In total, data from 106 speakers was analyzed to determine the course of linguistic change in the city of Erie and the current location of the dialect boundaries in the neighboring regions. In order to process the acoustic data from this large corpus, the methodology of transcription and subsequent forced alignment was applied. This enabled the automatic extraction of 113,245 vowel formant measurements, an amount which would have been difficult to obtain using the standard sociophonetic procedure of manual formant extraction. In order to reduce error in the formant measurements, automatic techniques for measurement point selection and formant prediction were developed. The acoustic analysis focuses on aspects of the vowel system that differentiate the North and the Midland. The results show that the merger of /o/ and /oh/ began in the city of Erie before 1900, and that it has subsequently spread to the town of Ripley, NY. Additionally, Erie speakers consistently have a nasal or continuous short-a system. On the other hand, Erie is still located on the Northern side of the boundary with respect to the fronting of the back upgliding vowels /uw/, /ow/, and /aw/. Finally, an analysis of the lexical and morphosyntactic variables shows a widespread acceptability of the Midland features in Erie. In the final section of the dissertation, the early settlement history of the region is examined, and Erie's acceptance of several Midland features is explained by the early presence of a large contingent of non-Northern, especially Scots-Irish, settlers. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]