The
West Branch Susquehanna River is one of the two principal branches, along with the North Branch, of the
Susquehanna River in the northeastern
United States. The North Branch, which rises in upstate
New York, is generally regarded as the extension of the main branch, with the shorter West Branch being its principal
tributary. The West Branch, which is long, is entirely within the state of
Pennsylvania, draining a large mountainous area within the
Allegheny Plateau in the western part of the state. Along most of its course it
meanders along mountain ridges and through
water gaps, forming a large zigzag arc through central Pennsylvania around the north end of the
Allegheny Ridge. In colonial times the river provided an important water route to the
Ohio River valley. In the 18th century, its lower valley became a significant industrial heartland of Pennsylvania. In the 20th century the upper reaches of the West Branch turned a yellow/orange color due to sulfurous drainage from nearby and abandoned deep bituminous coal mines.