Great Lakes nations maintain coast guard vessels in the Great Lakes. During settlement, the Great Lakes and its rivers were the only practical means of moving people and freight. Barges from middle North America were able to reach the Atlantic Ocean from the Great Lakes when the Welland canal opened in 1824 and the later Erie Canal opened in 1825. By 1848, with the opening of the Illinois and Michigan Canal at Chicago, direct access to the Mississippi River was possible from the lakes. With these two canals an all-inland water route was provided between New York City and New Orleans. The
Teltow Canal Berlin's eastern suburbs. The Dahme provides a link to the Oder-Spree Canal, and hence to the River Oder and Poland. Whilst the Dahme is a tributary of the River Spree, itself a navigable tributary of the Havel, the Teltow Canal offers the advantage of bypassing the centre of Berlin, with its heavy river traffic. At its western end, the Teltow Canal incorporates the Griebnitzsee lake which links to the Havel in Potsdam. The Griebnitz Canal provides a second link to the Havel from the eastern end of the Griebnitzsee. Towards its eastern end, the Teltow Canal is linked to the