<P> The Mississippi River has the world's fourth - largest drainage basin ("watershed" or "catchment"). The basin covers more than 1,245,000 square miles (3,220,000 km), including all or parts of 31 U.S. states and two Canadian provinces . The drainage basin empties into the Gulf of Mexico, part of the Atlantic Ocean . The total catchment of the Mississippi River covers nearly 40% of the landmass of the continental United States . The highest point within the watershed is also the highest point of the Rocky Mountains, Mount Elbert at 14,440 feet (4,400 m). </P> <P> In the United States, the Mississippi River drains the majority of the area between the crest of the Rocky Mountains and the crest of the Appalachian Mountains, except for various regions drained to Hudson Bay by the Red River of the North; to the Atlantic Ocean by the Great Lakes and the Saint Lawrence River; and to the Gulf of Mexico by the Rio Grande, the Alabama and Tombigbee rivers, the Chattahoochee and Appalachicola rivers, and various smaller coastal waterways along the Gulf . </P> <P> The Mississippi River empties into the Gulf of Mexico about 100 miles (160 km) downstream from New Orleans . Measurements of the length of the Mississippi from Lake Itasca to the Gulf of Mexico vary somewhat, but the United States Geological Survey's number is 2,320 miles (3,730 km). The retention time from Lake Itasca to the Gulf is typically about 90 days . </P> <P> The Mississippi River discharges at an annual average rate of between 200 and 700 thousand cubic feet per second (7,000--20,000 m / s). Although it is the fifth - largest river in the world by volume, this flow is a small fraction of the output of the Amazon, which moves nearly 7 million cubic feet per second (200,000 m / s) during wet seasons . On average, the Mississippi has only 8% the flow of the Amazon River . </P>

Where does the mississippi river enter the gulf