A slideshow illustrating the Mississippi river and the cities along it.

1. Mississippi River A journey through America’s heartland

2. The source In the vast pine forest of northern Minnesota is the beginning of the great river known to all the world as the Mighty Mississippi. At the Mississippi's source at Lake Itasca, the water is transparent and beautiful. You can actually remove your shoes and wade to the other side, or drop a twig in the water and imagine it floating to New Orleans.

3. The Legend of Paul Bunyan Only the great outdoors was big enough to accommodate Paul, and it was natural that he should become the World's Greatest Lumberjack.In the year of the 'Blue Snow' when it was so cold the geese flew backward, Paul found a baby ox in the snow. It was so cold, the ox and snow was blue. After Paul took him home and warmed him, his color stayed blue. Paul named him Babe. Like Paul, Babe grew fast and soon was seven ax handles and a plug of tobacco wide between the eyes. For a between meals snack, Babe would eat thirty bales of hay, wire and all. It took six men with picaroons to pick the wire out of his teeth. Babe hauled the huge camp tank wagon which was used to pave the winter logging roads with ice. When it sprang a leak one day, it created Lake Itasca south of Bemidji and the overflow trickled down to New Orleans to form the Mississippi River.

5. The source In the vast pine forest of northern Minnesota is the beginning of the great river known to all the world as the Mighty Mississippi.

6. Lake Itasca Lake Itasca At the Mississippi's source at Lake Itasca, the water is transparent and beautiful. You can actually remove your shoes and wade to the other side, or drop a twig in the water and imagine it floating to New Orleans.

7. Polluting the Gulf of Mexico The Minnesota River (lower branch), bearing sediments and nutrients, enters the Mississippi River at Fort Snelling State Park. These pollutants contribute to the “dead zone” in the Gulf of Mexico. Dead Zone

8. Railroad bridge under construction near LaCrosse, Wisconsin

9. Keelboats

10. Lock and dam flood containment program

11. Register’s Annual Great Bike Ride Across Iowa (RAGBRAI)

12. Davenport, Iowa floods

14. Riverboat gambling

15. Gateway Arch St. Louis, Missouri

17. Levees accentuate flooding The earthern dikes meant to protect low-lying areas from flooding increases flooding in other areas as the excess water has nowhere else to go but up.

18. Confluence with Ohio River

19. An artist's conception of downtown Cahokia. Monk's Mound and the main plaza sit within the palisade at the center of the site. The circle of posts at the far left may have been an observatory used to calculate significant dates in the calendar.

20. An artist's conception of downtown Cahokia. Monk's Mound and the main plaza sit within the palisade at the center of the site.

21. A solar calendar of the sun's movement helped determine when to hold ceremonies in preparation for planting, harvesting, and other events in the agricultural cycle and marked the all-important spring and fall equinox celebrations.

22. Three earthquakes that occurred in 1811 and 1812 near New Madrid, Mo. are among the great earthquakes of known history, affecting the topography more than any other earthquake on the North American continent. Failed Rift

23. Memphis, Tennessee

24. The great Mississippi Steamboat race

25. Sunset

26. New Orleans

27. The French Quarter Bourbon Street

28. Swamps

29. The Delta

30. Lake Pontchartrain & New Orleans 1995 N Lake Pontchartrain New Orleans Bridges Mississippi R. Madisonville Lake Maurepas L. Salvador L. Borgne Canal

31. Vanishing wetlands Over the past century, the nearly 1.3 million square mile watershed of the Mississippi River has experienced major environmental changes, including conversion of more than 80 percent of forested wetlands to agriculture and urban areas, channelization, dam construction, and river levees. The construction of massive structures that keep the river from switching channels has restricted sediment and freshwater supply to the flood plain.

32. Unintended consequences These changes have been especially damaging to the region's wetlands. The coastal wetlands associated with the Mississippi River delta make up nearly 40 percent of the total coastal salt marsh in the lower 48 states of the U.S. These wetlands are disappearing at an average rate of 25 square miles per year, about 50 acres each day. Fragile wetlands are readily damaged, directly and indirectly, by canals dredged for navigation and energy exploration.

33. Oil rigs line the horizon in coastal Louisiana's Grande Isle. The oil industry has been a large contributor to the economy of Louisiana but also has contributed to coastal erosion. Oil Wealth

34. Drilling for oil Over the last 100 years, Louisiana has lost over 400,000 hectares to open water. Prior to 1940, the majority of Louisiana's oil and gas fields were in freshwater. Subsidence, the rise in sea level, and loss of land have contributed to all but one oil field now being located in open saltwater. All of these fields are vulnerable to oil spills, particularly those directly offshore.

35. Technology pushes exploration Since the mid-1990s, the Gulf has experienced a resurgence, with computer-driven technological advances — and federal tax breaks on the royalties paid for drilling in leased government waters — opening new horizons in water as deep as 10,000 feet, hundreds of miles from shore. .

36. Levees accentuate flooding

37. Sunset