This expansion of the original (1970) Abingdon Historic District, in the seat of Washington County, includes properties located along Valley, King, Park, and Oak Hill streets, and White’s Mill Road, and at the eastern and western ends of Main Street. The Abingdon Historic District Extension contains several early-19th-century buildings.  However, it is primarily significant for its late-19th- and early-20th-century residential architecture. These dwellings exhibit a rich diversity of architectural styles and building practices from the 1870s to the 1920s. Styles represented include the Italianate, Queen Anne, Colonial Revival, Bungalow, and Tudor Revival. Anchoring the western end of the Valley Street extension is Sinking Spring Cemetery, which contains the graves of many of the town’s foremost citizens; and the William King High School, a visually prominent symbol of the county’s abiding concern for education.