Berkshire Hills (bûrkˈshər, –shĭr) [key], mountainous region of wooded hills with many small lakes and streams, W Mass. The Berkshires are a southern extension of the Green Mts., but the name is generally applied to all highlands in W Massachusetts. Mt. Greylock, 3,491 ft (1,064 m), is the highest point in the hills and in the state. Tourism is a principal industry. The Berkshire Hills have numerous summer and winter resorts, state parks, and forests. The Housatonic, Hoosic, and Westfield rivers drain the region. Pittsfield, North Adams, Great Barrington, and Lenox are the largest towns in the Berkshires.