A view from the river in the middle of America

Lake Itasca, part of the residue the glaciers left behind in Minnesota, is about 250 miles northwest of St. Paul. Out of the northern end of the lake, water bubbles between boulders along the shoreline. These are the headwaters of the Mississippi River. By the time the river has a defined channel, about 40 feet downstream, it is no more than six-to-eight feet wide. I watched a teenage boy wade across without getting his knees wet.

Two thousand five hundred fifty-two miles later, it empties into the Gulf of Mexico. At New Orleans, a hundred miles above the Gulf, the river is 200 feet deep and considerably more than a mile wide. The flow at New Orleans is 44,853,116 gallons every second.

This flood comes from 31 states and two Canadian provinces. The river dumps 495 million tons of silt a year into the Gulf. Most of it comes from the Missouri River which empties into the Mississippi a short distance above St. Louis. Mark Twain described it as "too thick to drink and too thin to plow." One might say that the Mississippi and the Missouri jointly are the instrument by which soil from the Great Plains and Rocky Mountains is transferred to southern Louisiana.

I recently spent two weeks on a paddle-wheel steamboat, the Mississippi Queen, going down the river from St. Paul. There were about 300 passengers on board, many had been there before. One woman said she had been on 50 cruises down the river, her was when her grandmother took her as a little girl. As a group, we were from all over the country, from the East Coast to Hawaii.

My original intention for joining the cruise was to go all the way to New Orleans, but hurricane Katrina made that impossible. Instead, we turned up the Ohio at Cairo, Ill., to Paducah, Ky., and then up the Tennessee River to Chattanooga.

This is a formidable river system. It has a hypnotic effect. You can (and I did) spend endless hours on deck simply watching the shoreline pass by - isolated houses, little towns, an occasional city, highways, lots of long freight trains. Many of the trains are carrying wheat that ordinarily would go on barges to New Orleans for export. Since Katrina, this wheat has been going by train to Portland, Ore.

The traffic on the river is mainly barges, each carrying 1,500 tons, heavy with coal to fuel electric power plants in the Tennessee Valley but also weighted down with just about anything else - butter, syrup, and molasses.

It would be hard to exaggerate the importance of the Mississippi River system as a transportation artery. One reason Jefferson made the Louisiana Purchase was to secure free passage through the port of New Orleans. But the river is more than a means of cheap transportation. It has military, political, social, and cultural importance as well.

The Union won the Civil War after it controlled the Mississippi, Ohio, and Tennessee rivers. Andrew Jackson's victory over the British in the Battle of New Orleans in the War of 1812 did a lot to propel him into the White House. Herbert Hoover's relief work in the flood of 1927 had the same effect on his presidential ambitions. After more than a century, Mark Twain's "Adventures of Huckleberry Finn" remains a classic of American literature and one of the first sensitive treatments of racism. Mississippi cities - New Orleans, Memphis, St. Louis - gave the world jazz, the quintessential American music.

Small towns along the river have their own pet prides. A talkative cab driver in Winona, Minn., bragged that Winona State College has students from India and Bangladesh. (What these students take home with them will probably be good, too, for the American image in South Asia.) The driver also said it was OK for Bush to invade Iraq ("Nobody stopped Hitler; we needed to stop Saddam."); but it's not OK to stay. The Winona Daily News showed its priorities by giving saturation coverage to an upcoming election on a school tax.

LaCrosse, Wis., is said to have more bars per thousand people than any other city in the United States. It is also the site of several elaborate churches, one of which - the Franciscan Sisters of Perpetual Adoration - has been carrying on a nonstop prayer for a hundred years. Those who pray do so in shifts and take requests.

Nauvoo, Ill., was the departure point for the Mormon journey that ended in Utah. The Mormon Church has bought most of the old town and restored it to the way it looked when Mormons lived there in the 19th century. There is a temple, a visitor center, a family life building, a drugstore (not functional), a bakery (they will give you cookies), a cultural center, and an ox-drawn wagon, a replica of those which crossed the plains 160 years ago. You can take a short ride around a park to get a feel for what travel used to be like.

Hannibal, Mo., lives off its history as the home of Mark Twain and the site of Tom Sawyer's adventures.

St. Louis was the starting point of the Lewis and Clark expedition which President Jefferson sent to find out what he had bought when he made the Louisiana Purchase. That momentous land deal is now commemorated by the Gateway Arch, 630 feet high - 75 feet taller than the Washington Monument.

Cape Girardeau, Mo., was a stop on the forced migration of Cherokee Indians from North Carolina to Oklahoma. It is also the hometown of Rush Limbaugh.

Savannah, Tenn., turned out a four-piece band and two belles in antebellum purple dresses, purple hats, and black gloves to meet us at the dock. Savannah is also the burial place of "Roots" author Alex Haley. A bus tour of the town took us to the Hardin County Visitors Bureau, Peebles Department Store, Wal-Mart, and several large houses dating from the turn of the 19th century. Before the tour started, a passenger asked the guide if we would be going by a Catholic church. He explained that he tried to visit a Catholic church in every town. He has been in 50 states and has visited a Catholic church in every one.

Decatur, Ala., like a lot of river towns, has an attractive waterfront park. It is a 30-minute bus ride from the Army's Redstone Arsenal and NASA's elaborate displays on the space program and its history. The MINC (military-industrial complex which Eisenhower warned against in his presidential farewell address) is well represented; Lockheed-Martin and Boeing are the principal backers.

Between them, the Coast Guard and the Army Corps of Engineers regulate just about everything on the river. The Coast Guard tests and licenses crew members and is responsible for port security. The Corps of Engineers is responsible for the river. It has been stabilized so that it no longer changes course so much and so often. A system of locks and dams above St. Louis has evened the flow between too much in the spring and too little in the fall.

Meanwhile, the river, in the words of perhaps the most popular song about it, "just keeps rolling along." It is a national treasure, a slice of middle America in the middle of America.

• Pat M. Holt is former chief of staff of the Senate Foreign Relations Committee.