The longest rivers of the United States include 38 that have main stems of at least long. The main stem is "the primary downstream segment of a river, as contrasted to its tributaries". The United States Geological Survey (USGS) defines a main-stem segment by listing coordinates for its two end points, called the source and the mouth. Some well-known rivers like the Connecticut River, Housatonic River, Atchafalaya, Willamette, and Susquehanna are not included in this list because their main stems are shorter than 500 miles.
Seven rivers in this list cross or form international boundaries. Three—the Milk River, the Red River of the North, and the Saint Lawrence River—begin in the United States and flow into Canada; two do the opposite (Yukon and Columbia). Also a segment of the Saint Lawrence River forms the international border between part of the province of Ontario, Canada, and the U.S. state of New York. Of these seven rivers, only the Milk River crosses the international border twice, leaving and then re-entering the United States. Two rivers, the Colorado and the Rio Grande, begin in the United States and flow into or form a border with Mexico. In addition, the drainage basins of the Mississippi and Missouri rivers extend into Canada, and the basin of the Gila River extends into Mexico.
Sources report hydrological quantities with varied precision. Biologist and author Ruth Patrick, describing a table of high-discharge U.S. rivers, wrote that data on discharge, drainage area, and length varied widely among authors whose works she consulted. "It seems," she said, "that the wisest course is to regard data tables such as the present one as showing the general ranks of rivers, and not to place too much importance on minor (10–20%) differences in figures."
Table The primary source for watershed and discharge data in the table below is Rivers of North America. Conflicting data from other sources, if the difference is greater than 10 percent, is reported in the notes. Discharge refers to the flow at the mouth. In the "States, provinces, and map" column, the superscripts "s" and "m" indicate "source" and "mouth". Non-U.S. states appear in italics. Except in the "States, provinces, and map" column, abbreviations are as follows: "km" for "kilometer", "mi" for "mile", "s" for "second", "m" for "meter", and "ft" for "foot".
Key River is not entirely within the United States. Watershed is not entirely within the United States.
+ Longest main-stem rivers of the United States#NameLengthStates, provinces, and mapSourcecoordinatesThe mouth coordinates and source coordinates are from the Geographic Names Information System (United States Geological Survey) or the Canadian Geographical Names Data Base except for the coordinates of the mouth of the Colorado River, derived by geolocating with Google Earth.MouthMouthcoordinatesWatershedareaFrom Rivers of North America (ed. Benke and Cushing) unless otherwise noted.DischargePhoto1Missouri River mi4,090 kmMontanas, North Dakota, South Dakota, Nebraska, Iowa, Kansas, MissourimMississippi River mi21,371,017 km2 ft3/s1,956 m3/s2Mississippi Rivermi3,766 kmMinnesotas, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, LouisianamGulf of Mexico mi23,270,000 km2 ft3/s18,400 m3/s3Yukon River mi3,190 kmBritish Columbias, Yukon Territory, AlaskamBering Sea mi2839,200 km2 ft3/s6,340 m3/s4Rio Grande mi2,830 kmColorados, New Mexico, Texasm, Chihuahua, Coahuila, Nuevo León, TamaulipasmGulf of Mexico mi2870,000 km2 ft3/s37 m3/s5Colorado River mi2,330 kmColorados, Utah, Arizona, Nevada, California, Sonoram, Baja CaliforniamGulf of CaliforniaDerived via Google Earth mi2642,000 km2 ft3/s40 m3/s6Arkansas River mi2,322 kmColorados, Kansas, Oklahoma, ArkansasmMississippi River mi2414,910 km2 ft3/s1,004 m3/s7Columbia River mi2,000 kmBritish Columbias, Washingtonm, OregonmPacific Ocean mi2724,024 km2 ft3/s7,730 m3/s8Red River mi1,811 kmOklahomas, Texas, Arkansas, LouisianamAtchafalaya and Mississippi rivers mi2169,890 km2 ft3/s852 m3/s9Snake River mi1,674 kmWyomings, Idaho, Oregon, WashingtonmColumbia River mi2281,000 km2 ft3/s1,565 m3/s10Ohio River mi1,575 kmPennsylvanias, Ohio, West Virginia, Indiana, Illinois, KentuckymMississippi River mi2529,000 km2 ft3/s8,733 m3/s11Colorado River of Texas mi1,560 kmTexass, mGulf of Mexico mi2103,341 km2 ft3/s75 m3/s12Tennessee River mi1,504 kmTennessees, Alabama, Mississippi, KentuckymOhio River mi2105,870 km2 ft3/s2,000 m3/s13Canadian River mi1,458 kmColorados, New Mexico, Texas, OklahomamArkansas River mi2122,070 km2 ft3/s174 m3/s14Brazos River mi1,390 kmTexass, mGulf of Mexico mi2115,566 km2 ft3/s249 m3/s15Green River mi1,230 kmWyomings, Colorado, UtahmColorado River mi2116,200 km2 ft3/s172 m3/s16Pecos River mi1,175 kmNew Mexicos, TexasmRio Grande mi2113,960 km2 ft3/s2 m3/s17White River (Arkansas) mi1,159 kmArkansass, m, MissouriMississippi River mi272,189 km2 ft3/s979 m3/s18James River mi1,140 kmNorth Dakotas, South DakotamMissouri River mi254,240 km2 ft3/s24.2 m3/s19Kuskokwim River mi1,130 kmAlaskas, mBering Sea mi2124,319 km2 ft3s1,900 m3/s20Cimarron River mi1,123 kmOklahomas, m, Colorado, Kansas Arkansas River mi250,540 km2 ft3/s42 m3/s21Cumberland River mi1,120 kmKentuckys, m, Tennessee Ohio River mi246,430 km2 ft3/s 862 m3/s 22Yellowstone River mi1,091 kmWyomings, Montana, North DakotamMissouri River mi2182,336 km2 ft3/s362 m3/s23North Platte River mi1,070 kmColorados, Wyoming, NebraskamPlatte River mi290,352 km2 ft3/s21.9 m3/s24Milk River mi1,005 kmAlberta, Montanas, mMissouri River mi257,839 km2 ft3/s18.9 m3/s25Ouachita River mi974 kmBenke and Cushing, p. 265Arkansass, LouisianamBlack River mi264,454 km2 ft3/s843 m3/s26St. Lawrence River mi965 kmNew Yorks, Ontarios, QuebecmGulf of St. Lawrence mi21,600,000 km2 ft3/s12,600 m3/s27Gila River mi960 kmNew Mexicos, ArizonamColorado River mi2149,832 km2 ft3/s6 m3/s28Sheyenne River mi951 kmNorth Dakotas, mRed River of the North mi223,000 km2 ft3/s8.2 m3/s29Tanana River mi940 kmAlaskas, mYukon River mi2114,000 km2 ft3/s1,185 m3/s30Smoky Hill River mi927 kmColorados, KansasmKansas River mi249,900 km2 ft3/s43.7 m3/s31Niobrara River mi914 kmWyomings, NebraskamMissouri River mi232,600 km2 ft3/s49 m3/s32Little Missouri River mi900 kmWyomings, Montana, South Dakota, North DakotamMissouri River mi221,500 km2 ft3/s13 m3/s33Sabine River mi890 kmTexass, LouisianamGulf of Mexico mi225,268 km2 ft3/s238 m3/s34Red River of the North mi890 kmNorth Dakotas, Minnesotas, ManitobamLake Winnipeg mi2287,500 km2 ft3/s236 m3/s35Des Moines River mi845 kmMinnesotas, Missouri, IowamMississippi River mi231,127 km2 ft3/s182 m3/s36White River (Missouri River) mi815 kmNebraskas, South DakotamMissouri River mi226,418 km2 ft3/s16 m3/s37Trinity River mi815 kmTexass, mGalveston Bay mi246,540 km2 ft3/s222 m3/s38Wabash River mi810 kmOhios, Indianam, IllinoismOhio River mi285,340 km2 ft3/s28 m3/s
Map
See also List of rivers of the United States List of rivers of the United States by discharge List of longest rivers in the United States by state List of longest streams of Idaho List of longest streams of Minnesota List of longest streams of Oregon List of rivers by length
Notes
References
Works cited