The Tennessee–Tombigbee Waterway (popularly known as the Tenn-Tom) is a artificial U.S. waterway built in the 20th century from the Tennessee River to the junction of the Black Warrior-Tombigbee River system near Demopolis, Alabama. The Tennessee–Tombigbee Waterway links commercial navigation from the nation's midsection to the Gulf of Mexico. The major features of the waterway are of navigation channels, a cut between the watersheds of the Tombigbee and Tennessee rivers, and ten locks and dams. The locks are , the same dimension as those on the Mississippi above Lock and Dam 26 at Alton, Illinois. Under construction for 12 years by the U.S. Army Corps of Engineers, the Tennessee–Tombigbee Waterway was completed in December 1984 at a total cost of nearly $2 billion. The Tenn-Tom encompasses 17 public ports and terminals, of land, and another managed by state conservation agencies for wildlife habitat preservation and recreational use. Early history and construction First proposed in the Colonial period, the idea for a commercial waterway link between the Tennessee and Tombigbee rivers did not receive serious attention until the advent of river steamboat traffic in the early nineteenth century. It stimulated trade throughout the river cities, and the ability to get products to the Gulf Coast for overseas shipping. As steamboat efficiency gains caused water transport costs to decline, in 1875 engineers surveyed a potential canal route for the first time. They issued a negative report, emphasizing that prohibitive cost estimates kept the project from economic feasibility. Enthusiasm for the project languished until the presidency of Franklin D. Roosevelt, who took office during the Great Depression and quickly conceived of investment in major infrastructure projects to put many of the unemployed to work. The development of the Tennessee River by the TVA, especially the construction of the Pickwick Lock and Dam in 1938, helped decrease the Tenn-Tom's potential economic costs and increase its potential benefits. Pickwick Lake's design included an embayment on its south shore at Yellow Creek, which would permit the design and construction of an entrance to a future southward waterway (leading to the Tombigbee River), should it be decided that such a waterway would be built in the future. Later, construction (under World War II emergency authorization) of Kentucky Dam at Gilbertsville, Kentucky, near the mouth of the Tennessee River's confluence with the Ohio River, would complete the "northern" half of the future waterway. As early as 1941 the