Mountain chain in the eastern United States, extending from the valley of the St. Lawrence River in Quebec, Canada, to the coastal plain of the Gulf of Mexico in Alabama.
- Location of the Appalachian Trail, the world's longest continuous hiking path. It extends over two thousand miles from Maine to Georgia.
- Historically, the Appalachian Mountains were a barrier to early western expansion. In the early 1840s, railroads began to transport settlers across the mountains, permitting access to the frontier.