Saint John River (Bay of Fundy) Saint John River (Bay of Fundy) The Saint John River (; Maliseet: "Wolastoq") is a river, approximately long, located principally in the Canadian province of New Brunswick, but also in and arising from three primary sources in the province of Quebec and the U.S. state of Maine. It forms part of the Canada–United States border in two different stretches along its length. The river drains an area of approximately , of which slightly more than half is located in New Brunswick. Along that portion of the Atlantic shoreline of North America that lies between the St. Lawrence River and the
Bay of Fundy various rivers which empty into it. Near the mouth of the Saint John River, where it passes through the city of Saint John, is the famous Reversing Falls. Here the changing tide causes alternating strong upriver and downriver flows several times a day as the tidal cycle changes. A narrow granite gorge and rocky bottom heavily restricts waterflow and creates strong rapids that flow upriver at high tide, and downriver at low tide. Rivers in the upper Bay of Fundy have a smaller flow-rate than the Saint John, and a shallower slope. As a result, extensive mud flats are deposited