The Mississippi River System, also referred to as the Western Rivers, is a mostly riverine network which includes 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...

 and connecting waterways.
From the perspective of natural geography

Geography

Geography is the science that studies the lands, features, inhabitants, and phenomena of Earth. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...

 and hydrology

Hydrology

Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...

, the system consists of the Mississippi River itself and its numerous natural tributaries

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...

 and distributaries

Distributary

A distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel. They are a common feature of river deltas. The phenomenon is known as river bifurcation. The opposite of a distributary is a tributary...

. The major tributaries are the Ohio

Ohio River

The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...

, Illinois

Illinois River

The Illinois River is a principal tributary of the Mississippi River, approximately long, in the State of Illinois. The river drains a large section of central Illinois, with a drainage basin of . This river was important among Native Americans and early French traders as the principal water route...

, 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...

, Red and Missouri

Missouri River

The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...

 Rivers and, indirectly, such major Ohio River tributaries as the Allegheny

Allegheny River

The Allegheny River is a principal tributary of the Ohio River; it is located in the Eastern United States. The Allegheny River joins with the Monongahela River to form the Ohio River at the "Point" of Point State Park in Downtown Pittsburgh, Pennsylvania...

, Tennessee

Tennessee River

The Tennessee River is the largest tributary of the Ohio River. It is approximately 652 miles long and is located in the southeastern United States in the Tennessee Valley. The river was once popularly known as the Cherokee River, among other names...

, and Wabash

Wabash River

The Wabash River is a river in the Midwestern United States that flows southwest from northwest Ohio near Fort Recovery across northern Indiana to southern Illinois, where it forms the Illinois-Indiana border before draining into the Ohio River, of which it is the largest northern tributary...

 rivers.
From the perspective of modern commercial navigation, the system includes the above as well as navigable inland waterways which are connected by artificial means. Important connecting waterways include the Illinois Waterway

Illinois Waterway

The Illinois Waterway system consists of of water from the mouth of the Calumet River to the mouth of the Illinois River at Grafton, Illinois. It is a system of rivers, lakes, and canals which provide a shipping connection from the Great Lakes to the Gulf of Mexico via the Mississippi River. The...

, the Tennessee-Tombigbee Waterway

Tennessee-Tombigbee Waterway

The Tennessee–Tombigbee Waterway is a 234-mile man-made, artificial waterway that extends from the Tennessee River to the junction of the Black Warrior-Tombigbee River system near Demopolis, Alabama, United States. The Tenneessee-Tombigbee Waterway links commercial navigation from the nation’s...

, and the Gulf Intracoastal Waterway

Gulf Intracoastal Waterway

The Gulf Intracoastal Waterway is the portion of the Intracoastal Waterway located along the Gulf Coast of the United States. It is a navigable inland waterway running approximately 1700 kilometers from Carrabelle, Florida, to Brownsville, Texas.The waterway provides a channel with a controlling...

. This system of waterways is maintained by the U.S. Army Corps of Engineers with a project depth of between 9 and 12 feet (2.7 – 3.7 m) to accommodate barge

Barge

A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and need to be towed by tugboats or pushed by towboats...

transportation, primarily of bulk commodities.