The Trans-Canada Highway winds along the Saint John and Madawaska rivers through New Brunswick and Quebec to the St. Lawrence River. It follows one of the oldest and strategically most important routes in North American history: the Grand Communications Route. For millennia, the Saint John River system had been a major artery in the vast system of lakes, rivers, and portages linking aboriginal communities. During the French and British colonial periods, and until the advent of rail travel in the 1870s, it remained the backbone of an overland route between the Atlantic Ocean and the interior of the continent. Today, the traveller along the Trans-Canada Highway can visit some of the forts that once defended this vital Road to Canada.