United States Marine Highway Program
The United States Marine Highway Program is a United States Department of Transportation (DOT) initiative authorized to increase use of the United States' 29,000 mi (47,000 km) of navigable waterways to alleviate traffic and wear to the nation's highways caused by tractor trailer traffic. The program is managed by the Maritime Administration's Office of Ports & Waterways Planning.
Source: Wikipedia — United States Marine Highway Program (CC BY-SA 4.0)