This list is incomplete; you can help by adding missing items. (April 2010)

This is a list of the longest undammed rivers of the world, ordered by length.

Continent color key
Africa Asia Europe North America Oceania South America
Length color key
Over 5,000 kilometres (3,100 mi) 3,000 to 5,000 kilometres (1,900 to 3,100 mi) 2,000 to 3,000 kilometres (1,200 to 1,900 mi) 1,000 to 2,000 kilometres (620 to 1,240 mi) Less than 1,000 kilometres (620 mi)
River Length Drainage area Average discharge (m³/s) Mouth Notes Reference Rank
Amazon River 6,937 km (4,310 mi)
6,992 km (4,345 mi) 		7,050,000 km2 (2,720,000 sq mi) 219,000 m3/s (7,700,000 cu ft/s) Atlantic Ocean Second-longest and largest river in the world, undammed as well as unbridged, does not form a delta while joining the sea due to adequate thrust of river water to overcome the sea water wave and tidal thrusts. 1
Lena River 4,472 km (2,779 mi) 2,500,000 km2 (970,000 sq mi) 17,000 m3/s (600,000 cu ft/s) Arctic Ocean Longest undammed river in Asia. 2
Amur–Shilka–Onon 4,197 km (2,608 mi) 1,855,000 km2 (716,000 sq mi) 11,700 m3/s (410,000 cu ft/s) Strait of Tartary 3
Mackenzie–Slave–Athabasca 3,403 km (2,115 mi) 1,805,200 km2 (697,000 sq mi) 10,700 m3/s (380,000 cu ft/s) Arctic Ocean The Peace–Finlay system would extend even longer from the head of the Slave but there are dams on the Peace. 4
Nizhnyaya Tunguska River 2,989 km (1,857 mi) 473,000 km2 (183,000 sq mi) 3,680 m3/s (130,000 cu ft/s) Yenisei River The Russian government is planning to build hydro dams on the river within the next few years. 5
Salween River 2,815 km (1,749 mi) 324,000 km2 (125,000 sq mi) 6,700 m3/s (240,000 cu ft/s) Andaman Sea Longest undammed Southeast Asian river. Burma is planning to build the Tasang Dam and several others. 6
Paraguay River 2,549 km (1,584 mi) 1,150,000 km2 (440,000 sq mi) 4,550 m3/s (161,000 cu ft/s) Paraná River 7
Amu Darya–Panj 2,500 km (1,600 mi) 534,700 km2 (206,400 sq mi) 1,330 m3/s (47,000 cu ft/s) Aral Sea (former) Although undammed, heavy diversion through canals causes the river to frequently dry up without reaching its mouth. Tajikistan is planning to build a hydroelectric dam on the Panj River. 8
Aldan River 2,273 km (1,412 mi) 729,000 km2 (281,000 sq mi) 5,060 m3/s (179,000 cu ft/s) Lena River
Rio Negro 2,230 km (1,390 mi) 691,000 km2 (267,000 sq mi) 29,300 m3/s (1,030,000 cu ft/s) Amazon River
Vitim River 1,978 km (1,229 mi) Lena River
Indigirka River 1,726 km (1,072 mi) 360,400 km2 (139,200 sq mi) 1,810 m3/s (64,000 cu ft/s) Arctic Ocean
Fraser River 1,375 km (854 mi) 220,000 km2 (85,000 sq mi) 3,475 m3/s (122,700 cu ft/s) Pacific Ocean
Kuskokwim River 1,165 km (724 mi) 120,000 km2 (46,000 sq mi) 1,900 m3/s (67,000 cu ft/s) Bering Sea
Back River 1,150 km (710 mi) Arctic Ocean
Anadyr River 1,150 km (710 mi) 191,000 km2 (74,000 sq mi) 2,020 m3/s (71,000 cu ft/s) Gulf of Anadyr
Liard River 1,115 km (693 mi) 277,100 km2 (107,000 sq mi) 2,434 m3/s (86,000 cu ft/s) Mackenzie River
Yellowstone River 1,114 km (692 mi) 181,300 km2 (70,000 sq mi) 380 m3/s (13,000 cu ft/s) Missouri River Longest undammed river in the contiguous United States.
Maya River 1,053 km (654 mi) 171,000 km2 (66,000 sq mi) 1,180 m3/s (42,000 cu ft/s) Aldan River
Fly River 1,050 km (650 mi) 76,000 km2 (29,000 sq mi) 6,500 m3/s (230,000 cu ft/s) Gulf of Papua Largest completely undammed river system in the world
White River 934 km (580 mi) 26,000 km2 (10,000 sq mi) 16 m3/s (570 cu ft/s) Missouri River
Tanana River 916 km (569 mi) 113,960 km2 (44,000 sq mi) 1,172 m3/s (41,400 cu ft/s) Yukon River
Thelon River 900 km (560 mi) 142,400 km2 (55,000 sq mi) Hudson Bay
Salmon River 684 km (425 mi) 36,000 km2 (14,000 sq mi) 310 m3/s (11,000 cu ft/s) Snake River
Stikine River 610 km (380 mi) 52,000 km2 (20,000 sq mi) 1,580 m3/s (56,000 cu ft/s) Pacific Ocean
Skeena River 570 km (350 mi) 54,400 km2 (21,000 sq mi) 1,760 m3/s (62,000 cu ft/s) Pacific Ocean
Susitna River 504 km (313 mi) 52,000 km2 (20,000 sq mi) 1,400 m3/s (49,000 cu ft/s) Pacific Ocean Alaska is planning to build a hydroelectric dam on the river at Devil's Canyon.

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