During the summer of 1902, scientist Alfred Brooks explored the flanks of the mountain as a part of an exploratory surveying party conducted by the U.S. Geological Survey.
The party landed at Cook Inlet in late May, then traveled east, paralleling the Alaska Range, before reaching the slopes of Denali in early August.
Camped on the flank of the mountain on August 3, Brooks noted later that while "the ascent of Mount McKinley had never been part of our plans," the party decided to delay one day so "that we might actually set foot on the slopes of the mountain."
Setting off alone, with good weather, on August 4, Brooks aimed to reach a 10,000 ft shoulder.
At 7,500 ft, Brooks found his way blocked by sheer ice and, after leaving a small cairn as a marker, descended.
After the party's return, Brooks co-authored a "Plan For Climbing Mt McKinley," published in National Geographic magazine in January, 1903, with fellow party-member and topographer D.L. Raeburn, in which they suggested that future attempts at the summit should approach from the north, not the south.
The report received substantial attention, and within a year, two climbing parties declared their intent to summit.

In the early summer of 1903, Judge James Wickersham, then of Eagle, Alaska, made the first recorded attempt to climb Denali, along with a party of four others.
The group attempted to get as close to the mountain as possible via the Kantishna river by steamer, before offloading and following Chitsia Creek with a poling boat, mules and backpacks, a route suggested to them by Tanana Athabaskan people they met along the way.
The party received further navigational assistance at Anotoktilon, an Athabaskan hunting camp, where residents gave the group detailed directions to reach the glaciers at the foot of Denali.
On reaching the mountain, the mountaineers set up base camp on the lower portion of Peters Glacier.
Aiming for the northwest buttress of Denali's north peak, they attempted to ascend directly, however crevasses, ice fall and the lack of a clear passage caused them to turn and attempt to follow a spur via Jeffery Glacier where they believed they could see a way to the summit.
After a dangerous ascent, at around 10,000 ft, Wickersham found that the route did not connect as it had appeared from below, instead discovering "a tremendous precipice beyond which we cannot go.
Our only line of further ascent would be to climb the vertical wall of the mountain at our left, and that is impossible."
This wall, now known as the Wickersham Wall, juts 14,000 ft upwards from the glacier to the north peak of Denali.
Because of the route's history of avalanche danger, it was not successfully climbed until 1963.

Later in the summer of 1903, Dr. Frederick Cook led a team of five men on another attempt at the summit.
Cook was already an experienced explorer and had been a party-member on successful arctic expeditions led both by Robert Peary and Roald Amundsen.
Yet he struggled to obtain funding for the expedition under his own leadership, eventually putting it together "on a shoestring budget" without any other experienced climbers.
The party navigated up the Cook inlet and followed the path of the 1902 Brooks party towards Denali.
Cook approached the mountain via the Peters Glacier, as Wickersham had done, however he was able to overcome the ice fall that had caused the previous group to turn up the spur towards the Wickersham Wall.
Despite avoiding this obstacle, on August 31, having reached an elevation of about 10,900 ft on the northwest buttress of the north peak, the party found they had reached a dead end and could make no further progress.
On the descent, the group completely circumnavigated the mountain, the first climbing party to do so.
 Although Cook's 1903 expedition did not reach the summit, he received acclaim for the accomplishment, a 1000 mile trek in which he not only circled the entire mountain but also found, on the descent, an accessible pass northeast of the Muldrow Glacier following the headwaters of the Toklat and Chulitna rivers.

In 1906, Cook
During the summer of 1902, scientist Alfred Brooks explored the flanks of the mountain as a part of an exploratory surveying party conducted by the U.S. Geological Survey. The party landed at Cook Inlet in late May, then traveled east, paralleling the Alaska Range, before reaching the slopes of Denali in early August. Camped on the flank of the mountain on August 3, Brooks noted later that while "the ascent of Mount McKinley had never been part of our plans," the party decided to delay one day so "that we might actually set foot on the slopes of the mountain." Setting off alone, with good weather, on August 4, Brooks aimed to reach a 10,000 ft shoulder. At 7,500 ft, Brooks found his way blocked by sheer ice and, after leaving a small cairn as a marker, descended. After the party's return, Brooks co-authored a "Plan For Climbing Mt McKinley," published in National Geographic magazine in January, 1903, with fellow party-member and topographer D.L. Raeburn, in which they suggested that future attempts at the summit should approach from the north, not the south. The report received substantial attention, and within a year, two climbing parties declared their intent to summit.
In the early summer of 1903, Judge James Wickersham, then of Eagle, Alaska, made the first recorded attempt to climb Denali, along with a party of four others. The group attempted to get as close to the mountain as possible via the Kantishna river by steamer, before offloading and following Chitsia Creek with a poling boat, mules and backpacks, a route suggested to them by Tanana Athabaskan people they met along the way. The party received further navigational assistance at Anotoktilon, an Athabaskan hunting camp, where residents gave the group detailed directions to reach the glaciers at the foot of Denali. On reaching the mountain, the mountaineers set up base camp on the lower portion of Peters Glacier. Aiming for the northwest buttress of Denali's north peak, they attempted to ascend directly, however crevasses, ice fall and the lack of a clear passage caused them to turn and attempt to follow a spur via Jeffery Glacier where they believed they could see a way to the summit. After a dangerous ascent, at around 10,000 ft, Wickersham found that the route did not connect as it had appeared from below, instead discovering "a tremendous precipice beyond which we cannot go. Our only line of further ascent would be to climb the vertical wall of the mountain at our left, and that is impossible." This wall, now known as the Wickersham Wall, juts 14,000 ft upwards from the glacier to the north peak of Denali. Because of the route's history of avalanche danger, it was not successfully climbed until 1963.
Later in the summer of 1903, Dr. Frederick Cook led a team of five men on another attempt at the summit. Cook was already an experienced explorer and had been a party-member on successful arctic expeditions led both by Robert Peary and Roald Amundsen. Yet he struggled to obtain funding for the expedition under his own leadership, eventually putting it together "on a shoestring budget" without any other experienced climbers. The party navigated up the Cook inlet and followed the path of the 1902 Brooks party towards Denali. Cook approached the mountain via the Peters Glacier, as Wickersham had done, however he was able to overcome the ice fall that had caused the previous group to turn up the spur towards the Wickersham Wall. Despite avoiding this obstacle, on August 31, having reached an elevation of about 10,900 ft on the northwest buttress of the north peak, the party found they had reached a dead end and could make no further progress. On the descent, the group completely circumnavigated the mountain, the first climbing party to do so.  Although Cook's 1903 expedition did not reach the summit, he received acclaim for the accomplishment, a 1000 mile trek in which he not only circled the entire mountain but also found, on the descent, an accessible pass northeast of the Muldrow Glacier following the headwaters of the Toklat and Chulitna rivers.
In 1906, Cook 
Denali