ONE of the murals depicting the history of Paducah on a wall built to keep out the river shows a captain in his pilot-house, looking over a 15-barge tow with 24,000 tonnes of cargo. At the turn of the last century this small city in Kentucky, at the confluence of the Ohio and Tennessee, became a hub of the inland-waterways system and the home of barge and tugboat companies, dry docks and repair shops. Its Centre for Maritime Education still trains river mariners all over the country.

Another mural shows Lock and Dam 52, about 17 miles downstream from Paducah on the Ohio river, which is now an emblem of America’s crumbling river infrastructure. Lock and Dam 52 and 53 are the busiest spots on the inland river-system, a bottleneck through which 135m tonnes of grain, coal, steel, iron, cement and other cargo move every year. Built in 1928 and 1929 by the Army Corps of Engineers, which maintains waterways, they should have been replaced in 1988, as locks have an expected lifespan of about 50 years. In 1988 Congress approved a budget of $775m to replace them within ten years. Almost 30 years later the Olmsted Locks and Dam, which will replace 52 and 53, is still under construction, in part because the Corps, to save money, experimented with building in the wet rather than making the dam in sections on dry land first. Costs have ballooned to more than $3bn; the project is forecast to be operational by 2024.