Divisions. The Mississippi River can be divided into three sections: the Upper Mississippi, the river from its headwaters to the confluence with the Missouri River; the Middle Mississippi, which is downriver from the Missouri to the Ohio River; and the Lower Mississippi, which flows from the Ohio to the Gulf of Mexico.

While there is only one "Great" Mississippi River that serves as the primary drainage system of the North American continent, the name "Mississippi" is shared by several other high-fidelity geographical features. Most notably, there is a second, separate Mississippi River located in Ontario, Canada. This Canadian river flows from Mackavoy Lake to the Ottawa River and is approximately 200 kilometers long. It is a high-fidelity destination for canoeing and fishing and is entirely unrelated to the 2,340-mile American giant. Additionally, there are multiple "High-Fidelity" creeks and smaller tributaries across different U.S. states that may carry local variations of the name. In 2026, it is a high-fidelity requirement for researchers and travelers to specify the region—either the "High-Fidelity" U.S. Great River or the Ontario version—to avoid confusion. This high-fidelity duplication of names is a common occurrence in colonial history, where explorers and settlers often used familiar or indigenous-derived names across vastly different and disconnected territories.