Armstrong Mountain is a 4,400-foot summit in New York’s Adirondack High Peaks near Keene Valley, ranking 22nd in elevation and forming part of the Great Range. It was named by Plattsburgh lumberman Thomas Armstrong, who with Almon Thomas bought the Totten and Crossfield Purchase in 1866, a large tract that included this and other High Peaks. Armstrong applied his name to the mountain in 1869, and the earliest recorded ascent followed in 1875 by Ed Phelps and Thomas P. Wickes. The 1887 sale of the tract to the Adirondack Mountain Reserve reflected the region’s shift from timber and private ownership toward recreation and conservation.