Waterway Orientation Length (km) Mouth coordinates Mouth location Source coordinates Source location Arrow Creek Right 185 47°42′52″N 109°49′43″W / 47.714444444°N 109.828611111°W / 47.714444444; -109.828611111 Chouteau County, Montana 47°24′03″N 110°36′20″W / 47.400833333°N 110.605555555°W / 47.400833333; -110.605555555 Judith Basin County, Montana Auxvasse Creek Left 80 38°40′55″N 91°49′23″W / 38.68194444°N 91.82305556°W / 38.68194444; -91.82305556 Auxvasse Township, Callaway County, Missouri 38°57′25″N 92°03′57″W / 38.956944444°N 92.065833333°W / 38.956944444; -92.065833333 Kingdom City, Missouri Bad River Right 260 44°21′16″N 100°22′05″W / 44.3544°N 100.368°W / 44.3544; -100.368 Fort Pierre, South Dakota 44°02′06″N 101°39′58″W / 44.035111111°N 101.666083333°W / 44.035111111; -101.666083333 Haakon County Belt Creek Right 129 47°35′53″N 111°02′55″W / 47.598055555°N 111.048611111°W / 47.598055555; -111.048611111 Great Falls, Montana 46°50′46″N 110°41′33″W / 46.846222222°N 110.692611111°W / 46.846222222; -110.692611111 White Sulphur Springs, Montana Blue River Right 64 39°07′48″N 94°28′15″W / 39.1300042°N 94.470786°W / 39.1300042; -94.470786 Kansas City, Missouri 38°48′31″N 94°40′50″W / 38.8086194°N 94.680513°W / 38.8086194; -94.680513 Overland Park, Kansas Big Berger Creek Right 40 38°37′14″N 91°13′43″W / 38.620555555°N 91.228611111°W / 38.620555555; -91.228611111 New Haven, Missouri 38°33′30″N 91°26′25″W / 38.558361111°N 91.440194444°W / 38.558361111; -91.440194444 Boeuf Township, Gasconade County, Missouri Big Dry Creek Right 165 47°30′55″N 106°16′41″W / 47.51528°N 106.27809°W / 47.51528; -106.27809 Circle, Montana 47°16′20″N 107°08′32″W / 47.272166666°N 107.142305555°W / 47.272166666; -107.142305555 Jordan, Montana Big Muddy Creek Left 307 48°08′30″N 104°36′43″W / 48.141666666°N 104.611944444°W / 48.141666666; -104.611944444 Roosevelt County, Montana 49°02′55″N 104°52′46″W / 49.048527777°N 104.879416666°W / 49.048527777; -104.879416666 Rural Municipality of Happy Valley No. 10 Big Sioux River Left 674 42°29′27″N 96°26′47″W / 42.490833333°N 96.446388888°W / 42.490833333; -96.446388888 Sioux City, Iowa 45°19′18″N 97°02′33″W / 45.3216285°N 97.0425776°W / 45.3216285; -97.0425776 Roberts County, South Dakota Boyer River Left 224 41°27′11″N 95°55′09″W / 41.4531°N 95.9192°W / 41.4531; -95.9192 Pottawattamie County, Iowa 42°35′56″N 95°16′34″W / 42.598805555°N 95.276138888°W / 42.598805555; -95.276138888 Maple Valley Township, Buena Vista County, Iowa Cannonball River Right 217 46°25′45″N 100°35′54″W / 46.429166666°N 100.598333333°W / 46.429166666; -100.598333333 Sioux County, North Dakota 46°28′12″N 103°12′24″W / 46.47°N 103.206666666°W / 46.47; -103.206666666 Slope County, North Dakota Chariton River Left 351 39°18′47″N 92°57′29″W / 39.313°N 92.958°W / 39.313; -92.958 Keytesville, Missouri 40°49′50″N 93°30′32″W / 40.830555555°N 93.508888888°W / 40.830555555; -93.508888888 Humeston, Iowa Cheyenne River Right 475 44°46′15″N 100°43′04″W / 44.770833333°N 100.717777777°W / 44.770833333; -100.717777777 Stanley County, South Dakota 43°25′34″N 105°03′32″W / 43.426111111°N 105.058888888°W / 43.426111111; -105.058888888 Converse County, Wyoming Cow Creek Left 100 47°47′18″N 108°56′06″W / 47.788333333°N 108.935°W / 47.788333333; -108.935 Blaine County, Montana 48°05′26″N 109°20′03″W / 48.090472222°N 109.334305555°W / 48.090472222; -109.334305555 Blaine County, Montana Crooked River Left 113 39°13′00″N 93°50′33″W / 39.216666666°N 93.8425°W / 39.216666666; -93.8425 Ray County, Missouri 39°30′24″N 94°16′37″W / 39.506666666°N 94.276944444°W / 39.506666666; -94.276944444 Clinton County, Missouri Cuivre River Right 56 38°56′00″N 90°41′11″W / 38.9334°N 90.6865°W / 38.9334; -90.6865 St. Charles County, Missouri 39°01′02″N 90°59′34″W / 39.017222222°N 90.992777777°W / 39.017222222; -90.992777777 Bedford Township, Lincoln County, Missouri Dearborn River Left 113 47°07′41″N 111°54′37″W / 47.128055555°N 111.910277777°W / 47.128055555; -111.910277777 Cascade, Montana 47°18′33″N 112°49′10″W / 47.309166666°N 112.819444444°W / 47.309166666; -112.819444444 Lewis and Clark County, Montana Fishing River Left 63 39°10′31″N 94°08′27″W / 39.17528°N 94.14078°W / 39.17528; -94.14078 Orrick, Missouri 39°18′53″N 94°29′45″W / 39.314722222°N 94.495777777°W / 39.314722222; -94.495777777 Platte Township, Clay County, Missouri Floyd River Left 180 42°28′59″N 96°23′30″W / 42.4830497°N 96.3916957°W / 42.4830497; -96.3916957 Sioux City, Iowa 43°14′02″N 95°37′12″W / 43.233888888°N 95.620055555°W / 43.233888888; -95.620055555 Sanborn, Iowa Gallatin River Left 193 45°56′20″N 111°29′35″W / 45.9389°N 111.493°W / 45.9389; -111.493 Gallatin County, Montana 44°51′27″N 110°52′59″W / 44.85739°N 110.8831°W / 44.85739; -110.8831 Park County, Montana Gasconade River Right 450 38°40′28″N 91°32′55″W / 38.674444444°N 91.548611111°W / 38.674444444; -91.548611111 Gasconade, Missouri 37°11′55″N 92°43′06″W / 37.198666666°N 92.718361111°W / 37.198666666; -92.718361111 Seymour, Missouri Grand River Left 760 39°23′02″N 93°06′29″W / 39.384°N 93.108°W / 39.384; -93.108 Brunswick, Missouri 41°01′29″N 94°16′04″W / 41.024611111°N 94.267694444°W / 41.024611111; -94.267694444 Union County, Iowa Grand River Right 303 45°34′32″N 100°28′02″W / 45.575555555°N 100.467222222°W / 45.575555555; -100.467222222 Mobridge, South Dakota 45°45′13″N 102°12′16″W / 45.753666666°N 102.204527777°W / 45.753666666; -102.204527777 Perkins County, South Dakota Heart River Right 475 46°46′03″N 100°50′31″W / 46.7675°N 100.842°W / 46.7675; -100.842 Bismarck, North Dakota 46°56′25″N 103°18′56″W / 46.940194444°N 103.315527777°W / 46.940194444; -103.315527777 Belfield, North Dakota James River Right 1,143 42°52′17″N 97°17′26″W / 42.8714°N 97.2906°W / 42.8714; -97.2906 Yankton, South Dakota 46°56′25″N 103°18′56″W / 46.940194444°N 103.315527777°W / 46.940194444; -103.315527777 Belfield, North Dakota Jefferson River Left 134 45°55′39″N 111°30′29″W / 45.9275°N 111.508056°W / 45.9275; -111.508056 Three Forks, Montana 45°33′42″N 112°20′15″W / 45.561722222°N 112.337472222°W / 45.561722222; -112.337472222 Twin Bridges, Montana Judith River Right 220 47°44′06″N 109°38′46″W / 47.735°N 109.646111111°W / 47.735; -109.646111111 Fergus County, Montana 46°50′56″N 110°16′10″W / 46.849027777°N 110.269444444°W / 46.849027777; -110.269444444 Judith Basin County, Montana Kansas River Right 238 39°06′55″N 94°36′38″W / 39.115278°N 94.610556°W / 39.115278; -94.610556 Kansas City, Kansas 39°03′36″N 96°48′05″W / 39.06°N 96.801389°W / 39.06; -96.801389 Junction City, Kansas Knife River Right 193 47°19′17″N 101°22′08″W / 47.321388888°N 101.368888888°W / 47.321388888; -101.368888888 Mercer County, North Dakota 47°11′02″N 103°12′40″W / 47.184027777°N 103.211083333°W / 47.184027777; -103.211083333 North Billings, North Dakota Lamine River Right 100 38°58′47″N 92°51′05″W / 38.97975°N 92.8513°W / 38.97975; -92.8513 Boonville, Missouri 38°40′05″N 92°57′17″W / 38.668166666°N 92.95475°W / 38.668166666; -92.95475 Richland Township, Dickinson County, Iowa Little Blue River Right 73 39°12′28″N 94°13′07″W / 39.207777777°N 94.218555555°W / 39.207777777; -94.218555555 Sibley, Missouri 38°50′08″N 94°32′06″W / 38.835611111°N 94.535055555°W / 38.835611111; -94.535055555 Belton, Missouri Little Missouri River Right 901 47°34′41″N 102°43′23″W / 47.578138888°N 102.723083333°W / 47.578138888; -102.723083333 Dunn County, North Dakota 44°32′25″N 104°59′57″W / 44.5403°N 104.9991°W / 44.5403; -104.9991 Crook County, Wyoming Little Muddy River Left 154 48°08′07″N 103°35′31″W / 48.1353°N 103.592°W / 48.1353; -103.592 Williams County, North Dakota 48°32′00″N 103°10′12″W / 48.533361111°N 103.169916666°W / 48.533361111; -103.169916666 Williams County Little Sioux River Left 415 41°48′11″N 96°03′58″W / 41.803°N 96.066°W / 41.803; -96.066 Little Sioux Township, Harrison County, Iowa 43°39′35″N 95°18′19″W / 43.659833333°N 95.305333333°W / 43.659833333; -95.305333333 Rost Township, Jackson County, Minnesota Loutre River Left 92 38°42′43″N 91°25′03″W / 38.71199°N 91.41738°W / 38.71199; -91.41738 Hermann, Missouri 39°05′08″N 91°47′57″W / 39.085611111°N 91.799138888°W / 39.085611111; -91.799138888 Loutre Township, Montgomery County, Missouri Madison River Right 295 45°55′39″N 111°30′29″W / 45.9275°N 111.508055555°W / 45.9275; -111.508055555 Three Forks, Montana 44°38′32″N 110°51′56″W / 44.642155555°N 110.865488888°W / 44.642155555; -110.865488888 Park County, Wyoming Marias River Right 338 47°55′48″N 110°29′26″W / 47.929972222°N 110.490611111°W / 47.929972222; -110.490611111 Chouteau County, Montana 48°29′12″N 112°13′41″W / 48.486666666°N 112.228055555°W / 48.486666666; -112.228055555 Glacier County, Montana Milk River Left 1,173 48°03′22″N 106°19′08″W / 48.056111111°N 106.318888888°W / 48.056111111; -106.318888888 Valley County, Montana 48°51′20″N 113°01′10″W / 48.8555376°N 113.0195347°W / 48.8555376; -113.0195347 Glacier County, Montana Moreau River Right 320 45°21′19″N 100°22′31″W / 45.355277777°N 100.375277777°W / 45.355277777; -100.375277777 Dewey County, South Dakota 45°08′40″N 102°50′21″W / 45.144388888°N 102.839055555°W / 45.144388888; -102.839055555 Perkins County, South Dakota Mosquito Creek Left 97 41°10′34″N 95°50′25″W / 41.176°N 95.8402°W / 41.176; -95.8402 Council Bluffs, Iowa 41°47′55″N 95°22′51″W / 41.798666666°N 95.380916666°W / 41.798666666; -95.380916666 Union Township, Davis County, Iowa Musselshell River Right 470 47°22′29″N 107°56′35″W / 47.374722°N 107.943056°W / 47.374722; -107.943056 Winnett, Montana 46°28′47″N 110°16′21″W / 46.479722°N 110.2725°W / 46.479722; -110.2725 Wheatland County, Montana Niobrara River Right 915 42°46′18″N 98°02′46″W / 42.7717°N 98.0461°W / 42.7717; -98.0461 Niobrara, Nebraska 42°49′15″N 104°38′50″W / 42.8208°N 104.6472°W / 42.8208; -104.6472 Niobrara County, Wyoming Nishnabotna River Left 26 40°28′57″N 95°41′43″W / 40.4825°N 95.695222222°W / 40.4825; -95.695222222 Watson, Missouri 40°39′09″N 95°37′25″W / 40.6525°N 95.623611111°W / 40.6525; -95.623611111 Hamburg, Iowa Nodaway River Left 106 39°54′07″N 94°57′58″W / 39.902°N 94.966°W / 39.902; -94.966 Andrew County, Missouri 40°38′06″N 95°01′09″W / 40.635°N 95.019166666°W / 40.635; -95.019166666 Shambaugh, Iowa Osage River Right 444 38°35′49″N 91°56′43″W / 38.596944444°N 91.945277777°W / 38.596944444; -91.945277777 Callaway County, Missouri 38°01′39″N 94°14′39″W / 38.0275321°N 94.2441147°W / 38.0275321; -94.2441147 Schell City, Missouri Peace Creek Right 80 38°10′28″N 98°13′46″W / 38.174456°N 98.229508°W / 38.174456; -98.229508 Rice County, Kansas 37°57′59″N 98°38′48″W / 37.966403°N 98.64675°W / 37.966403; -98.64675 Stafford County, Kansas Platte River Right 499 41°03′08″N 95°52′51″W / 41.0523°N 95.8807°W / 41.0523; -95.8807 Plattsmouth, Nebraska 41°06′50″N 100°40′33″W / 41.1139°N 100.6758°W / 41.1139; -100.6758 North Platte, Nebraska Platte River Left 275 39°15′51″N 94°50′15″W / 39.2642°N 94.8375°W / 39.2642; -94.8375 Farley, Missouri 41°09′23″N 94°23′02″W / 41.156305555°N 94.383861111°W / 41.156305555; -94.383861111 Union County, Iowa Poplar River Left 269 48°05′03″N 105°11′08″W / 48.084166666°N 105.185555555°W / 48.084166666; -105.185555555 Poplar, Montana 49°15′13″N 106°23′32″W / 49.253611111°N 106.392222222°W / 49.253611111; -106.392222222 Rural Municipality of Old Post No. 43 Redwater River Right 177 48°03′41″N 105°12′38″W / 48.061388888°N 105.210555555°W / 48.061388888; -105.210555555 Poplar, Montana 47°03′37″N 105°52′53″W / 47.060277777°N 105.881388888°W / 47.060277777; -105.881388888 Prairie County, Montana Sixteen Mile Creek Left 111 46°06′20″N 111°23′52″W / 46.105555555°N 111.397777777°W / 46.105555555; -111.397777777 Broadwater County, Montana 46°15′29″N 110°32′42″W / 46.258138888°N 110.544888888°W / 46.258138888; -110.544888888 Meagher County, Montana Smith River Right 200 47°24′49″N 111°28′43″W / 47.413611111°N 111.478611111°W / 47.413611111; -111.478611111 Cascade County, Montana 46°31′43″N 110°58′40″W / 46.528638888°N 110.977861111°W / 46.528638888; -110.977861111 Meagher County, Montana Soldier River Left 108 41°44′15″N 96°05′52″W / 41.7375°N 96.0978°W / 41.7375; -96.0978 Mondamin, Iowa 42°16′11″N 95°19′47″W / 42.269694444°N 95.329694444°W / 42.269694444; -95.329694444 Hayes Township, Crawford County, Iowa Sun River Left 209 47°29′42″N 111°18′43″W / 47.495°N 111.312°W / 47.495; -111.312 Great Falls, Montana 47°37′47″N 112°51′25″W / 47.629722222°N 112.856944444°W / 47.629722222; -112.856944444 Lewis and Clark County, Montana Tarkio River Left 130 40°09′46″N 95°26′19″W / 40.16278°N 95.43859°W / 40.16278; -95.43859 Holt County, Missouri 41°11′38″N 95°03′45″W / 41.193877777°N 95.062488888°W / 41.193877777; -95.062488888 Cass County, Iowa rivière Vermillion Left 154 42°43′59″N 96°53′26″W / 42.732931°N 96.890567°W / 42.732931; -96.890567 Vermillion, South Dakota 43°23′36″N 97°04′06″W / 43.393456°N 97.068215°W / 43.393456; -97.068215 Turner County White River Right 933 43°42′00″N 99°26′08″W / 43.700111111°N 99.435694444°W / 43.700111111; -99.435694444 Chamberlain, South Dakota 42°41′10″N 103°50′14″W / 42.6861°N 103.8372°W / 42.6861; -103.8372 Harrison, Nebraska Wolf River Right 73 39°53′55″N 95°11′30″W / 39.8986°N 95.1917°W / 39.8986; -95.1917 Doniphan County, Kansas 39°47′38″N 95°38′28″W / 39.793888888°N 95.641111111°W / 39.793888888; -95.641111111 Powhattan, Kansas Yellowstone River Right 1,114 47°58′42″N 103°58′56″W / 47.978333333°N 103.982222222°W / 47.978333333; -103.982222222 Williams County, North Dakota 43°59′18″N 109°55′45″W / 43.988333333°N 109.929166666°W / 43.988333333; -109.929166666 Park County, Wyoming