Appalachian English, also known in the United States as Southern Mountain English, is American English native to the Appalachian mountain region of the Eastern United States. Historically, the term "Appalachian dialect" refers to a local English variety of southern Appalachia, though Appalachian English today geographically encompasses multiple varieties, predominantly including Western Pennsylvania English as spoken in northern Appalachia and regional Southern U.S. English as spoken in central and southern Appalachia. In fact, the Atlas of North American English identifies the "Inland South" dialect region, in which Southern U.S. English's defining vowel shift is the most evolved, as centering squarely in southern Appalachia, around the cities of Knoxville and Chattanooga, Tennessee; Birmingham, Alabama; and Asheville, North Carolina. All Appalachian English is rhotic and characterized by distinct phonology, morphology, syntax, and lexicon. It is mostly oral but its features are also sometimes represented in literary works.
Extensive research has been conducted since the 1930s to determine the origin of the Appalachian dialect. One popular theory is that the dialect is a preserved remnant of 16th-century (or "Elizabethan") English in isolation, though a far more accurate comparison would be to 18th-century (or "colonial") English; regardless, the Appalachian dialect studied within the last century, like most dialects, actually shows a mix of both older and newer features.