The Juniata River is a tributary of the Susquehanna River, approximately 104 miles (167 km) long, in central Pennsylvania in the United States. The river is considered scenic along much of its route, having a broad and shallow course passing through several mountain ridges and steeply-lined water gaps. It formed an early 18th-century frontier region in Pennsylvania and was the site of Native American attacks against white settlements during the French and Indian War. The watershed of the river encompasses an area of approximately 3,400 square miles (8,800 km2), approximately one-eighth of the drainage area of the Susquehanna. Approximately two-thirds of the watershed is forested. It is the second largest tributary of the Susquehanna after the West Branch Susquehanna.