Taconic Mountains (təkŏnˈĭk) [key], range of the Appalachian Mts., extending c.150 mi (240 km) north-south between the Green Mts. and the Hudson Valley along parts of New York's border with Vermont, Massachusetts, and Connecticut. Mt. Equinox (3,816 ft/1,163 m) is the highest point. The Taconics, among the oldest mountains in North America, have been worn low by millions of years of erosion. The Berkshire Hills, W Mass., are part of the range. Taconic State Park along the N.Y.-Mass. and N.Y.-Conn. borders is a popular recreational area.