Famed explorer Dr. Frederick Cook claimed the first ascent of the mountain in 1906. His claim was regarded with some suspicion from the start, but was also widely believed. It was later proved false, with some crucial evidence provided by Bradford Washburn when he was sketched on a lower peak.
In 1910, four locals (Tom Lloyd, Peter Anderson, Billy Taylor, and Charles McGonagall), known as the Sourdough expedition, attempted McKinley, despite a complete lack of climbing experience. They spent approximately three months on the mountain. However, their purported summit day was impressive: carrying a bag of doughnuts, each a thermos of hot chocolate, and a 14-foot (4.2 m) spruce pole, two of them reached the North Summit, the lower of the two, and erected the pole near the top. According to them, they took a total of 18 hour–a record that has yet to be breached (as of 2006). No one believed their success (partly due to false claims that they had climbed both summits) until the true first ascent, in 1913.
In 1912, the Parker-Browne expedition nearly reached the summit, turning back within just a few hundred yards of it due to harsh weather. In fact, that probably saved their lives, as a powerful earthquake shattered the glacier they ascended hours after they safely left it.
The first ascent of the main summit of McKinley came on June 7, 1913, by a party led by Hudson Stuck. The first man to reach the summit was Walter Harper, an Alaska Native. Harry Karstens and Robert Tatum also made the summit. Tatum later commented, "The view from the top of Mount McKinley is like looking out the windows of Heaven!" They ascended the Muldrow Glacier route pioneered by the earlier expeditions, which is still often climbed today. Stuck confirmed, via binoculars, the presence of a large pole near the North Summit; this report confirmed the Sourdough ascent, and today it is widely believed that the Sourdoughs did succeed on the North Summit. However, the pole was never seen before or since, so there is still some doubt. Stuck also discovered that the Parker-Browne party were only about 200 feet (61 m) of elevation short of the true summit when they turned back.
The mountain is regularly climbed today; in 2003, around 58% of climbers reached the top. But by 2003, the mountain had claimed the lives of nearly 100 mountaineers over time. The vast majority of climbers use the West Buttress Route, pioneered in 1951 by Bradford Washburn, after an extensive aerial photographic analysis of the mountain. Climbers typically take two to four weeks to ascend the mountain.
- 1896–1902: Surveys by Robert Muldrow, George Eldridge, Alfred Brooks.
- 1903: First attempt, by Judge James Wickersham.
- 1906: Frederick Cook falsely claims the first ascent of McKinley.
- 1910: The Sourdoughs ascend the North Summit.
- 1912: The Parker-Browne attempt almost reaches the South Summit.
- 1913: First ascent by Hudson Stuck, Walter Harper, Harry Karstens, Robert Tatum.
- 1932: Second ascent, by Alfred Lindley, Harry Liek, Grant Pearson, Erling Strom. (Both peaks were climbed.)
- 1947: Barbara Washburn becomes the first woman to reach the summit as her husband Bradford Washburn becomes the first to summit twice.
- 1951: First ascent of the West Buttress Route, led by Bradford Washburn.
- 1954: First ascent of the very long South Buttress Route.
- 1959: First ascent of the West Rib, now a popular, mildly technical route to the summit.
- 1961: First ascent of the Cassin Ridge, the best-known technical route on the mountain. This was a major landmark in Alaskan climbing.
- 1963: Two teams make first ascents of two different routes on the Wickersham Wall.
- 1967: First winter ascent, via the West Buttress, by Dave Johnston, Art Davidson and Ray Genet.
- 1967: Seven members of Joe Wilcox's twelve-man expedition perish, while stranded for ten days near the summit, in what has been described as the worst storm on record. Up to that time, this was the third worst disaster in mountaineering history in terms of lives lost.
- 1970: First solo ascent by Naomi Uemura.
- 1972: Sylvain Saudan, "Skier of the Impossible", skis down the sheer southwest face, conquered for the first time by skier or climber.
- 1979: First ascent by dog team achieved by Susan Butcher, Ray Genet, Brian Okonek, Joe Redington, Sr., and Robert Stapleton.
- 1984: Uemura returns to make the first winter solo ascent, but dies after summitting. Tono Križo, František Korl and Blažej Adam from the Slovak Mountaineering Association climb a very direct route to the summit, now known as the Slovak Route, on the south face of the mountain, to the right of the Cassin Ridge.
- 1988: First solo winter ascent with safe return, by Vern Tejas.
- 1997: First successful ascent up the West Fork of Traleika Glacier up to Karstens Ridge beneath Browne Tower. This path was named the "Butte Direct" by the two climbers Jim Wilson and Jim Blow.