Ridgeway started his mountaineering career in the late '60s and early '70s, making first ascents and new routes on a series of expeditions to the Peruvian Andes. In 1976 he joined the American Bicentennial Everest Expedition, and that led to joining the 1978 expedition to K2. Ridgeway and his three teammates were the first Americans to summit K2, the world's second highest mountain (8,611 m/28,251 ft) located in the Karakoram range. K2 is known for the inherent danger in climbing it, featuring a steep pyramidal relief and long sections of rock and ice, and unstable, overhanging serac. On September 6, 1978, Jim Wickwire and Louis Reichardt reached the summit of K2 via the Abruzzi Spur. The following day, Rick Ridgeway and John Roskelley abandoned a direct finish on the NE Ridge, and traversed under the summit pyramid to reach the summit via the Abruzzi finish. Ridgeway, Roskelley and Reichardt accomplished the feat without the use of supplemental oxygen.