The Connecticut River, the largest and longest river in New England, rises in northernmost New Hampshire, just south of the Quebec border. After coursing southward through a series of lakes, the river angles southwestward, becoming the border between New Hampshire and Vermont and receiving numerous tributaries from the northwest flank of the White Mountains. At St. Johnsbury, Vermont, the Connecticut begins a more southerly course, entering the basin of Glacial Lake Hitchcock, which extends southward to central Connecticut, just below Hartford; Lake Hitchcock formed late in the Pleistocene (some 15,000 years ago) when glacial meltwater was dammed by a moraine; layers of sediment accumulated for over 3000 years before lake waters broke through the moraine, draining southeastward to Long Island Sound.
Receiving numerous tributaries from the east slope of Vermont's Green Mountains, the west flank of New Hampshire's mountain corridor and the east wall of the Berkshires of western Massachusetts and northwestern Connecticut, the Connecticut River carries an abundant supply of sand and silt to Long Island Sound, producing vast, shifting sandbars and negating the establishment of a seaport at its mouth. Numerous dams disrupt its course and Quabbin Reservoir, constructed in the 1930s siphons off much of the flow from one of the Connecticut's major tributaries, the Chicopee River; this massive reservoir, the largest body of water in New England, supplies water to Greater Boston and much of eastern Massachusetts.
Tidal waters reach almost 60 miles into south-central Connecticut and rich wetlands flank lower portions of the river, home to a tremendous diversity of aquatic wildlife and a magnet for migrant flocks of waterfowl and shorebirds. Some 410 miles south and 2700 feet below its source, New England's Great River meets the sea.
