Potomac River

Potomac River
Great Falls of the Potomac River in June 2017 [1]
The Potomac River watershed covers the District of Columbia and parts of four states.
Native name	Patawomeck (Algonquian languages)
Location
Country	United States
State	West Virginia, Maryland, Virginia, District of Columbia
Cities	Cumberland, MD; Harpers Ferry, WV; Washington, D.C.; Alexandria, VA
Physical characteristics
Source	North Branch
• location	Fairfax Stone, Preston County, West Virginia
• coordinates	39°11′43″N 79°29′28″W / 39.19528°N 79.49111°W / 39.19528; -79.49111
• elevation	3,060 ft (930 m)
2nd source	South Branch
• location	Near Monterey, Highland County, Virginia
• coordinates	38°25′30″N 79°36′27″W / 38.425°N 79.6075°W / 38.425; -79.6075
Source confluence
• location	Green Spring, West Virginia
• coordinates	39°31′39″N 78°35′15″W / 39.5275°N 78.5875°W / 39.5275; -78.5875
Mouth	Chesapeake Bay
• location	St. Mary's County, Maryland/Northumberland County, Virginia, United States
• coordinates	38°00′00″N 76°20′06″W / 38°N 76.335°W / 38; -76.335
• elevation	0 ft (0 m)
Length	405 mi (652 km)
Basin size	14,700 sq mi (38,000 km2)
Discharge
• location	Little Falls, near Washington, D.C. (non-tidal; water years: 1931–2018)[2]
• average	11,498 cu ft/s (325.6 m3/s) (1931–2018)
• minimum	4,017 cu ft/s (113.7 m3/s) (2002)
• maximum	484,000 cu ft/s (13,700 m3/s) (1936)
Discharge
• location	Point of Rocks, Maryland
• average	9,504 cu ft/s (269.1 m3/s)
Discharge
• location	Hancock, Maryland
• average	4,168 cu ft/s (118.0 m3/s)
Discharge
• location	Paw Paw, West Virginia
• average	3,376 cu ft/s (95.6 m3/s)
Basin features
Tributaries
• left	Conococheague Creek, Antietam Creek, Monocacy River, Rock Creek, Anacostia River
• right	Cacapon River, Shenandoah River, Goose Creek, Occoquan River, Wicomico River
Waterfalls	Great Falls, Little Falls
Note: Since 1996, the Potomac has been the 'sister river' of the Ara River of Tokyo, Japan[3]

The Potomac River (/pəˈtoʊmək/ ^ⓘ) is a major river in the Mid-Atlantic region of the United States that flows from the Potomac Highlands in West Virginia to the Chesapeake Bay in Maryland. It is 405 miles (652 km) long,^[4] with a drainage area of 14,700 square miles (38,000 km²),^[5] and is the fourth-largest river along the East Coast of the United States.^{[citation needed]} More than 6 million people live within its watershed.^[6]

The river forms part of the borders between Maryland and Washington, D.C., on the left descending bank, and West Virginia and Virginia on the right descending bank. Except for a small portion of its headwaters in West Virginia, the North Branch Potomac River is considered part of Maryland to the low-water mark on the opposite bank. The South Branch Potomac River lies completely within the state of West Virginia except for its headwaters, which lie in Virginia. All navigable parts of the river were designated as a National Recreation Trail in 2006,^[7] and the National Oceanic and Atmospheric Administration designated an 18-square-mile (47 km²) portion of the river in Charles County, Maryland, as the Mallows Bay–Potomac River National Marine Sanctuary in 2019.^[8]

The river has significant historical and political significance, as the nation's capital of Washington, D.C. is located on its banks, as is Mount Vernon, the home of "Father of his Country" George Washington. During the American Civil War, the river became the boundary between the Union and the Confederacy, and the Union's largest army, the Army of the Potomac, was named after the river.