Mount Washington is located on a plateau in the Taconic Mountains. To the east, Mount Everett, the highest point in town and the highest point in the southern Taconic Mountains, rises near the town's eastern border. To the north, several mountains and hills lie along the Egremont town line. Alander Mountain and the western escarpment of the southern Taconic Mountains lie along the western border of Mount Washington at the Columbia County, New York line. To the south, along the Connecticut border, stands another series of peaks including Mount Frissell. Although the summit of this mountain rests within the town of Mount Washington, its southern slope is located in Connecticut and is that state's highest elevation. Many brooks lie within the town, most of which feed into Roeliff Jansen Kill in Copake, New York. Mount Washington State Forest makes up a large portion of the town, as does Mount Everett State Reservation. The town is also home to Bash Bish Falls State Park, which is centered around its eponymous falls. The Appalachian Trail enters Massachusetts in Mount Washington, coming from Bear Mountain, then turning east before following near the eastern town border, over Mount Race and Mount Everett, before heading into Egremont.
