Lock and Dam #53 on the Ohio River were under water when we visited because the river was up, which means traffic can navigate through the channel over the top of the dam and thus bypass the lock. Conversation with the Lock and Dam staff helped us understand the vagaries of managing river traffic and water flow. Present-day tugs can push 15 barges at once, moving freight much more efficiently than by road, and over 150 million tons of freight is moved over the Ohio River each year. The Olmstead project, started in 1992 and taking 20 years and 1 $billion to complete, is replacing Locks and Dams #52 and #53 which were built in the '20s.