Every visitor to New Orleans ought to take at least a short stroll on the Mississippi River levee to see if Old Man River is still rollin' along. For while the mighty river constantly flows by the city, and is actually several feet higher than the city, from the streets it is hidden from view and you might easily forget it is there. But without it there would be no New Orleans. The river has shaped the geography of a huge part of the USA, and it has factored in much of the country's history as well.

The Mississippi is no lazy river. You won't see anyone in their right mind attempt to swim across it. Through New Orleans, the river's depth averages about 200 feet. Its immense volume of water and sand roils with tremendous, turbulent force, whirling and eddying and scouring at the banks of snakelike curves.

It runs some 2400 miles from Minnesota to the Gulf of Mexico, and its drainage baisin extends from the Rockies to the Alleghenies, covering 40 percent of the continental US. All of the rain that falls in this vast area ends up, ultimately, in the Gulf, and most of it is carried there by the Mississippi. The Platte, the Missouri, the Ohio, the Cumberland and the Arkansas - mighty rivers themselves - all feed into the Mississippi, which carries their waters past New Orleans. The Mississippi drains more water than the Nile. Only the Amazon and the Congo carry a greater volume of water to the sea.

Along with all that water, the Mississippi moves up to several million tons of sediment into the Gulf every day. Thus, the river has transported more than 1000 cubic miles of earth from north to south, depositing soil into the Gulf and spreading it to the east and west as the river changed its course. The land that is Louisiana and much of Mississippi and Alabama was created by the river.

The river's name is a corruption of the old Ojibwe Misi-ziibi ('great river'). For early European settlers to the Mississippi Valley, the river initially proved too unruly to serve as a viable route into the heart of the country. The advent of the steamboat in 1807 changed that. During the early part of the 19th century New Orleans' population mushroomed, largely as a result of river traffic and trade. The river connects major cities such as Minneapolis, St Louis, Memphis, Baton Rouge and New Orleans.

It is natural for deltaic rivers to flood regularly and periodically change course, and preventing the Mississippi from flooding is no simple engineering feat. The river has proved more than mere levees can handle on several occasions, most notoriously in 1927, when the river breached levees in 145 places. That spring, some 27,000 square miles of farmland, from Illinois to Southern Louisiana, turned into a raging sea, up to 30 feet deep in places, that flowed steadily down to the Gulf. Entire towns were washed away and a million people were driven from their homes. It took several months for the flooding to recede back to within the river's banks. New Orleans, however, remained high and dry, as north of the city the floodwaters chose the Atchafalaya River's shorter path to the Gulf.

There are numerous benches along the levee in the French Quarter, which on mild sunny days call out for a picnic. The levee is good for a stretch of the legs. You can also get out on the water by hopping aboard the Canal St Ferry or a steamboat river cruise. Indeed, a short ferry ride from the foot of Canal St to Algiers Point is the easiest way to get out on the Mississippi River and admire New Orleans from the traditional river approach. Ride on the lower deck next to the water, and you're likely to see the state bird, the brown pelican. The state-run ferry is free and runs between 06:00 and midnight, leaving Canal St on the hour and half-hour, and returning from Algiers on the quarter-hour.