List of longest rivers of the United States (by main stem)
The main stems of 38 rivers in the United States are at least long. The main stem is "the primary downstream segment of a river, as contrasted to its tributaries". The United States Geological Survey 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 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. Two—the Yukon and Columbia rivers—begin in Canada and flow into the United States. Three—the Milk and Saint Lawrence rivers and the Red River of the North—begin in the United States and flow into Canada. Of these, 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 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 image" column, the superscripts "s" and "m" indicate "source" and "mouth". Non-U.S. states appear in italics. Except in the "States, provinces, and image" column, abbreviations are as follows: "km" for "kilometer", "mi" for "mile", "s" for "second", "m" for "meter", and "ft" for "foot".| # | Name | Mouth | Length | Source coordinates | Mouth coordinates | Watershed area | Discharge | States, provinces, and image |
| 1 | Missouri River | Mississippi River | 2341 mi 3,768 km | 529353 mi2 1,371,017 km2 | 69100 ft3/s 1,956 m3/s | Montanas, North Dakota, South Dakota, Nebraska, Iowa, Kansas, Missourim | ||
| 2 | Mississippi River | Gulf of Mexico | 2202 mi 3,544 km | 1260000 mi2 3,270,000 km2 | 650000 ft3/s 18,400 m3/s | Minnesotas, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, Louisianam | ||
| 3 | Yukon River | Bering Sea | 1979 mi 3,185 km | 324000 mi2 839,200 km2 | 224000 ft3/s 6,340 m3/s | British Columbias, Yukon Territory, Alaskam | ||
| 4 | Rio Grande | Gulf of Mexico | 1759 mi 2,830 km | 340000 mi2 870,000 km2 | 1300 ft3/s 37 m3/s | Colorados, New Mexico, Texasm, Chihuahua, Coahuila, Nuevo León, Tamaulipasm | ||
| 5 | Colorado River | Gulf of California | 1450 mi 2,330 km | 248000 mi2 642,000 km2 | 1400 ft3/s 40 m3/s | Colorados, Utah, Arizona, Nevada, California, Sonoram, Baja Californiam | ||
| 6 | Arkansas River | Mississippi River | 1443 mi 2,322 km | 160200 mi2 414,910 km2 | 35500 ft3/s 1,004 m3/s | Colorados, Kansas, Oklahoma, Arkansasm | ||
| 7 | Columbia River | Pacific Ocean | 1243 mi 2,000 km | 279548 mi2 724,024 km2 | 273000 ft3/s 7,730 m3/s | British Columbias, Washingtonm, Oregonm | ||
| 8 | Red River | Atchafalaya and Mississippi rivers | 1125 mi 1,811 km | 65590 mi2 169,890 km2 | 30100 ft3/s 852 m3/s | Oklahomas, Texas, Arkansas, Louisianam | ||
| 9 | Snake River | Columbia River | 1040 mi 1,674 km | 108000 mi2 281,000 km2 | 55300 ft3/s 1,565 m3/s | Wyomings, Idaho, Oregon, Washingtonm | ||
| 10 | Ohio River | Mississippi River | 979 mi 1,575 km | 204000 mi2 529,000 km2 | 308400 ft3/s 8,733 m3/s | Pennsylvanias, Ohio, West Virginia, Indiana, Illinois, Kentuckym | ||
| 11 | Colorado River of Texas | Gulf of Mexico | 970 mi 1,560 km | 39900 mi2 103,341 km2 | 2600 ft3/s 75 m3/s | Texass, m | ||
| 12 | Tennessee River | Ohio River | 935 mi 1,504 km | 40880 mi2 105,870 km2 | 71000 ft3/s 2,000 m3/s | Tennessees, Alabama, Kentuckym | ||
| 13 | Canadian River | Arkansas River | 906 mi 1,458 km | 47130 mi2 122,070 km2 | 6100 ft3/s 174 m3/s | Colorados, New Mexico, Texas, Oklahomam | ||
| 14 | Brazos River | Gulf of Mexico | 860 mi 1,390 km | 44620 mi2 115,566 km2 | 8800 ft3/s 249 m3/s | Texass, m | ||
| 15 | Green River | Colorado River | 760 mi 1,230 km | 44900 mi2 116,200 km2 | 6100 ft3/s 172 m3/s | Wyomings, Colorado, Utahm | ||
| 16 | Pecos River | Rio Grande | 730 mi 1,175 km | 44000 mi2 113,960 km2 | 71 ft3/s 2 m3/s | New Mexicos, Texasm | ||
| 17 | White River | Mississippi River | 720 mi 1,159 km | 27872 mi2 72,189 km2 | 34600 ft3/s 979 m3/s | Arkansass, m, Missouri | ||
| 18 | James River | Missouri River | 710 mi 1,140 km | 20942 mi2 54,240 km2 | 854 ft3/s 24.2 m3/s | North Dakotas, South Dakotam | ||
| 19 | Kuskokwim River | Bering Sea | 702 mi 1,130 km | 48000 mi2 124,319 km2 | 67000 ft3s 1,900 m3/s | Alaskas, m | ||
| 20 | Cimarron River | Arkansas River | 698 mi 1,123 km | 19510 mi2 50,540 km2 | 1500 ft3/s 42 m3/s | Oklahomas, m, Colorado, Kansas | ||
| 21 | Cumberland River | Ohio River | 696 mi 1,120 km | 17930 mi2 46,430 km2 | 30400 ft3/s 862 m3/s | Kentuckys, m, Tennessee | ||
| 22 | Yellowstone River | Missouri River | 678 mi 1,091 km | 70400 mi2 182,336 km2 | 12800 ft3/s 362 m3/s | Wyomings, Montana, North Dakotam | ||
| 23 | North Platte River | Platte River | 665 mi 1,070 km | 34885 mi2 90,352 km2 | 770 ft3/s 21.9 m3/s | Colorados, Wyoming, Nebraskam | ||
| 24 | Milk River | Missouri River | 625 mi 1,005 km | 22332 mi2 57,839 km2 | 670 ft3/s 18.9 m3/s | Alberta, Montanas, m | ||
| 25 | Ouachita River | Black River | 605 mi 974 km | 24886 mi2 64,454 km2 | 29800 ft3/s 843 m3/s | Arkansass, Louisianam | ||
| 26 | Saint Lawrence River | Gulf of Saint Lawrence | 600 mi 965 km | 620000 mi2 1,600,000 km2 | 440000 ft3/s 12,600 m3/s | New Yorks, Ontarios, Quebecm | ||
| 27 | Gila River | Colorado River | 600 mi 960 km | 57850 mi2 149,832 km2 | 210 ft3/s 6 m3/s | New Mexicos, Arizonam | ||
| 28 | Sheyenne River | Red River of the North | 591 mi 951 km | 8800 mi2 23,000 km2 | 288 ft3/s 8.2 m3/s | North Dakotas, m | ||
| 29 | Tanana River | Yukon River | 584 mi 940 km | 44000 mi2 114,000 km2 | 41800 ft3/s 1,185 m3/s | Alaskas, m | ||
| 30 | Smoky Hill River | Kansas River | 576 mi 927 km | 19260 mi2 49,900 km2 | 1542 ft3/s 43.7 m3/s | Colorados, Kansasm | ||
| 31 | Niobrara River | Missouri River | 568 mi 914 km | 12600 mi2 32,600 km2 | 1700 ft3/s 49 m3/s | Wyomings, Nebraskam | ||
| 32 | Little Missouri River | Missouri River | 560 mi 900 km | 8310 mi2 21,500 km2 | 450 ft3/s 13 m3/s | Wyomings, Montana, South Dakota, North Dakotam | ||
| 33 | Sabine River | Gulf of Mexico | 553 mi 890 km | 9756 mi2 25,268 km2 | 8400 ft3/s 238 m3/s | Texass, Louisianam | ||
| 34 | Red River of the North | Lake Winnipeg | 550 mi 890 km | 111000 mi2 287,500 km2 | 8300 ft3/s 236 m3/s | North Dakotas, Minnesotas, Manitobam | ||
| 35 | Des Moines River | Mississippi River | 525 mi 845 km | 12018 mi2 31,127 km2 | 6400 ft3/s 182 m3/s | Minnesotas, Missouri, Iowam | ||
| 36 | White River | Missouri River | 506 mi 815 km | 10200 mi2 26,418 km2 | 570 ft3/s 16 m3/s | Nebraskas, South Dakotam | ||
| 37 | Trinity River | Galveston Bay | 506 mi 815 km | 17970 mi2 46,540 km2 | 7800 ft3/s 222 m3/s | Texass, m | ||
| 38 | Wabash River | Ohio River | 503 mi 810 km | 32950 mi2 85,340 km2 | 1001 ft3/s 28 m3/s | Ohios, Indianam, Illinoism |