Cool river facts

Length: Hard to say, because the river’s winding channel is constantly changing. The best estimates put it between 2,300 and 2,500 miles.

Width: 20 to 30 feet at the headwaters; four miles wide at Lake Onalaska (near LaCrosse, Wis.), where a dam on the Black River helps hold water in the river channel. The widest natural point on the river is Lake Pepin, with a width of 2 miles.

Depth: Less than 3 feet at the headwaters; about 200 feet deep near New Orleans.

Elevation: 1,475 feet above sea level at the headwaters; it loses more than half of that before leaving Minnesota, and then gradually descends to sea level where it enters the Gulf of Mexico.

Sediment load: The river carries an average of 436,000 tons of sediment each day. That adds up to 159 million tons over the course of a year. Dirt weighs about 120 pounds per cubic foot, so that’s enough dirt every day to make a pile 220 feet wide at the bottom and 144 feet tall — the height of a 14-story building. In a year it would make a pile 1,320 feet across and 1,455 feet high — six times wider and a little higher than the Sears Tower in Chicago.

Current speed: 1.2 mph at the headwaters; 3 mph at New Orleans. A raindrop falling on the headwaters at Lake Itasca would take about 90 days to reach the Gulf of Mexico.

Flow rate: 6 cubic feet per second at the headwaters, meaning if you were standing on the bank and not moving, six cubic feet of water would flow past you every second — barely enough to fill a standard bathtub in two seconds. At New Orleans, the average flow rate is 600,000 cubic feet per second — enough to fill 44,500 bathtubs every second.

Where does all that water come from? The Mississippi’s water shed covers 41 percent of the continental United States, encompassing 31 states and two Canadian provinces. Any rainwater or snow melt in that area that doesn’t trickle down into underground aquifers ends up in the river.

Agriculture: All that water and sediment produces rich farmland. 92 percent of the United States’ agriculture exports come from the Mississippi River basin.

Shipping: The river is a highway, too: 850 miles of it are navigable to barges. 60 percent of U.S. grain exports (accounting for 78 percent of all grain exports worldwide) are shipped down the Mississippi to freighters waiting in New Orleans. The Ports of New Orleans and South Louisiana and Baton Rouge cover 172 miles of riverbank, and together form the largest port in the world in terms of tonnage shipped.

Wildlife: 60 percent of all North American birds use the Mississippi River basin as their migratory path. The river and its tributaries are home to 241 species of fish.

Boundaries: Minnesota is the only state the Mississippi flows through; it forms the border of nine other states.

Locks and dams: Of the 850 navigable miles, 670 are reachable only because of 29 locks that mark the river between Minneapolis and St. Louis. 10 are either in Minnesota are on a stretch of the river that Minnesota shares with Wisconsin.