The Elk River is a 35.2 miles (56.6 km) tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Neosho River

Neosho River

The Neosho River is a tributary of the Arkansas River in eastern Kansas and northeastern Oklahoma in the United States. Its tributaries also drain portions of Missouri and Arkansas. The river is about long. Via the Arkansas, it is part of the Mississippi River watershed.- Course :The Neosho's...

 in southwestern Missouri

Missouri

Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...

 and northeastern Oklahoma

Oklahoma

Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Its tributaries also drain a small portion of northwestern Arkansas

Arkansas

Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...

. Via the Neosho and Arkansas

Arkansas River

The Arkansas River is a major tributary of the Mississippi River. The Arkansas generally flows to the east and southeast as it traverses the U.S. states of Colorado, Kansas, Oklahoma, and Arkansas. The river's initial basin starts in the Western United States in Colorado, specifically the Arkansas...

 rivers, the Elk is part of the Mississippi River

Mississippi River

The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

 watershed

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

.

Course

The Elk is formed by the confluence of Big Sugar Creek

Big Sugar Creek

Big Sugar Creek is a waterway in the Ozark Mountains of southwest Missouri. The creek starts near the Arkansas state line. Only about of this is floatable during the spring and summer. The gradient is near 9 feet per mile from Highway 90 to Cyclone and 6 feet per mile to Pineville, Missouri. Big...

 and Little Sugar Creek at Pineville, Missouri

Pineville, Missouri

Pineville is a city in and the county seat of McDonald County, Missouri, United States. The population was 916 at the 2009 census, at which time it was a town. It is part of the Fayetteville–Springdale–Rogers, AR-MO Metropolitan Statistical Area....

, and flows generally westward through McDonald County, Missouri

McDonald County, Missouri

McDonald County is a county located in Southwest Missouri in the United States of America. As of the 2010 U.S. Census, the population was 23,083. Its county seat is Pineville...

, past the town of Noel

Noel, Missouri

Noel is a city in McDonald County, Missouri, United States, along the Elk River. The population was 1,615 at the 2009 census. It is part of the Fayetteville–Springdale–Rogers Metropolitan Area....

, into Delaware County, Oklahoma

Delaware County, Oklahoma

Delaware County is a county located in the U.S. state of Oklahoma. As of 2000, the population was 37,077 and the newest population estimate is 45,000. Its county seat is Jay. The county was named for the Delaware Indians resettled in what was then Indian Territory in the 1830s. .Delaware County...

, where it meets the Neosho River. Most of the river's course in Oklahoma is part of the Grand Lake o' the Cherokees

Grand Lake o' the Cherokees

Grand Lake o' the Cherokees is situated in Northeast Oklahoma, nestled in the foothills of the Ozark Mountain Range. The "o'" in the name of the lake stands for of not over. Grand Lake Of the Cherokees is the official name. It is often simply called Grand Lake...

, an impoundment formed by Pensacola Dam

Pensacola Dam

The Pensacola Dam, also known as the Grand River Dam, is a multiple-arch buttress dam on the Grand River in-between Disney and Langley in the U.S. state of Oklahoma. The dam is operated by the Grand River Dam Authority and creates Grand Lake o' the Cherokees...

on the Neosho.