THE GREAT LOOP
The Great Loop became possible with the completion of U.S. and Canadian canals: Erie Canal (1827), Rideau (1826), Trent Severn Waterway (1850-1920) and the Welland Canal (1824). These land-cut channels connected the Eastern Seaboard with the Great Lakes. The completion of the Illinois and Michigan Canal (1848) connected Lake Michigan to the Illinois and Mississippi Rivers to the Gulf of Mexico.
In 1900 congress funded the Atlantic Intracoastal Waterway from Boston to the Florida Keys, completed in 1935. In 1985 the Tenn-Tom Waterway allowed for a more regulated, short-cut route to Mobile Bay and the Gulf of Mexico.
An early account of a circumnavigation is A Year in a Yawl, the tale of four boys from St. Joseph, MI, who slid a homemade sailboat through the Illinois and Michigan Canal, then the Mississippi to the Gulf and around the Keys. At the Erie Canal they bought an old gray mare that pulled them through the Canal.