Potomac River

The Potomac [pəˈtoʊmək] ( listen^{? /i}) is a river in the eastern United States, which flows from its origin in West Virginia after about 616 km into the Chesapeake Bay.

Its two headwaters, the North Branch Potomac River and the South Branch Potomac River, join about 10 miles southeast of Cumberland on the Maryland-West Virginia border. In its course, the river forms parts of the boundaries between Maryland, West Virginia, Virginia and the District of Columbia. Due to errors made by the English crown administration in the concession deeds (royal charters), the river was mistakenly granted to Maryland and Virginia on both sides, leading to a nearly 150-year conflict between the two states. This was resolved by the 1785 Mount Vernon Compact and the 1877 Black-Jenkins Award; since then, the river has belonged to Maryland on both sides up to Virginia's low-water line.

Before entering the Chesapeake Bay, the river reaches a width of 8 to 13 km. The United States Geological Survey operates a gauging station in Washington, D.C.. There, the annual mean discharge is 316 m³/s. The highest ever measured was 3944 m³/s, and the lowest was observed on February 17, 2008, at 1.9 m³/s.

Potomac is the Europeanized spelling of Patowmeck, the Algonkin name of a Native American village. The spelling of the name has changed in many steps over the years, from Patawomeke on explorer John Smith's map to Patawomeck and Patowmack. In 1931, the United States Board on Geographic Names established the official river name as the Potomac.

During the War of Secession, the watercourse played an important role in the operations of both armies due to the frequently changing course of the front. The largest Union army was named the Army of the Potomac because of its area of operations.

Potomac is also the name of a riverside village in Montgomery County, about 20 kilometers from Washington, D.C.. Near the village of Potomac are the great waterfalls of the Potomac River.

Potomac also refers to a Powhatan Federation tribe that succeeded in uniting some 30 to 40 Algonkin tribes.

The asteroid (1345) Potomac, discovered in 1908 by Joel Hastings Metcalf, is named after the Potomac.