Denali, also known as Mount McKinley, in Alaska, is the tallest mountain in North America, at 6,189 metres (many sources incorrectly give a height of 6,194 metres which was based on a 1956 survey that was superseded in 1989). In fact, measured from its base on a 2000-foot plateau in Denali National Park to its summit, it is taller than Mount Everest; Everest rests atop the Tibetan Plateau, and therefore its base is already at an altitude of 5,200 metres. Along with Mauna Kea, Denali can make a plausible claim to be the world's tallest mountain (measured from base to summit); Mauna Kea is larger, but the greater part of it is underwater. On land, Denali has no equal as a free-standing mountain.

Why not Mount McKinley? Wikipedia has decided to use the name more commonly known around the world, which was officially given to the mountain in 1896 in recognition of William McKinley, who was then the Governor of Ohio, and went on to become the 25th President of the United States. The name was given by William Dickey, a gold prospector who was part of the Cook Inlet Stampede in 1896, who wrote an article for the New York Sun describing the mountain and claiming it as North America's tallest. His reasoning for the name (as then-Governor McKinley seems never to have visited Alaska) had more to do with scoring points off his prospecting rivals than wanting to immortalize McKinley:

"When later asked why he named the mountain after McKinley, Dickey replied that the verbal bludgeoning he had received from free silver partisans had inspired him to retaliate with the name of the gold standard champion."
- Terris Moore, Mt. McKinley: The Pioneer Climbs

The name was always controversial - the native Athabaskan people already had a much better and more evocative name, Denali, which means "The Great One", and after Hudson Stuck became the first to reach the summit in 1913 he published his memoir of the ascent under the title The Ascent of Denali, making a heartfelt plea for this name in his preface:

"Forefront in this book, because forefront in the author's heart and desire, must stand a plea for the restoration to the greatest mountain in North America of its immemorial native name."

In 1980 the State of Alaska officially adopted Denali as the mountain's name, and renamed Mount McKinley National Park to Denali National Park. However, the United States Board of Geographic Names has not recognized the change, maintaining the name McKinley due to its wide recognition and in order to distinguish the mountain easily from the National Park on maps. The controversy continues, with different sources insisting on using one name or the other, but it seems certain that over time, as the name Denali becomes more widely known, the native name will be adopted as it has been for the majority of great mountains around the world.

Although Denali is much smaller than the "8000ers", the world's highest and most famous peaks, it is not by any means easy to climb. As previously mentioned, in real terms it is taller than Everest, in the sense that climbers will have much further to go from the base. In addition, it is among the coldest mountains in the world (only the Antarctic peaks have a lower average summit temperature), with a recorded temperature extreme of -100° Fahrenheit (-73.3° Celsius). Due to its latitude (its exact location is 63° 07' N, 151° 01' W) there is also much less oxygen available than there would be at a comparable height closer to the equator, due to the troposphere being thinner at the Earth's poles; therefore, it carries as high a risk of altitude sickness as any of the bigger Himalayan peaks.

Denali has been subject to massive glaciation and ice erosion, and is still the source of five major glaciers - the Peters Glacier on the northwest, the Muldrow Glacier to the northeast, the Traleika Glacier on the east, the Ruth Glacier to the southeast and the Kahlitna Glacier to the southwest. These glaciers comprise part of most of the major routes up the mountain, and also a lot of its dangers, as cracks and fissures may appear and disappear in the ice, trapping unwary climbers.

It has two major summits - the South is the main one, and the North summit rises to 5,934 metres; the North summit is rarely climbed as it is reached via a different route. The first attempt on Denali was in 1903 by James Wickersham, a district judge for Alaska, by an exceptionally difficult and dangerous route along the Peters Glacier and the North Face (which was subsequently named the Wickersham Wall). He didn't make it to the summit, but he didn't die either, which considering the avalanche danger on that route can be considered a victory. This route wasn't successfully climbed until 1963.

Frederick Cook, a famous explorer, tried again in 1906. Cook, who was embroiled for much of his life in a bitter feud with rival explorer Robert Peary over which of them reached the North Pole first, claimed to have reached Denali's summit, but his evidence was highly suspicious and is now considered to have been refuted. Incidentally, the North Pole issue between himself and Peary has also since been resolved: both of their stories have been completely discredited.

Denali was almost summited in 1910 by a group of local Alaskan men collectively known as the Sourdough Expedition. They had absolutely no climbing experience and practically no equipment, and spent 3 months on the mountain. They claimed afterwards to have reached both summits, which has since been proven false, but 2 of their members may well have reached the North Summit, reportedly carrying "a bag of doughnuts, a thermos of cocoa each and a 14-foot spruce pole" (Wikipedia). Yet another attempt was made in 1912, when the Parker-Browne Expedition was forced to turn back within a few hundred metres of the summit due to the weather. As it turned out, this was a blessing in disguise - a few hours after they descended, an earthquake shattered the glacier that their route had followed, and it's likely that if they had pressed on to the summit and then returned, they would have been caught in the destruction and killed.

Finally in 1913 Hudson Stuck led a successful team to the summit - the first climber to reach the top was Walter Harper, a native Alaskan. They used a route up the Muldrow Glacier which is still frequently used in modern times. They were also able to establish that there was a large pole near the North Summit, which seemed to verify that the Sourdough Expedition really did make it that far.

Although still dangerous, Denali doesn't claim as many lives as it used to, and the standard route via the Western Buttress, which was worked out in 1951 after Bradford Washburn studied arial photographs of the entire massif, is relatively safe and free of technical difficulty. There have been 96 deaths on the mountain as of 2006; since more than 1,000 people come to climb the mountain every year, this isn't too bad, and the official fatality rate (deaths compared to successful summits) is approximately 3%, lower than almost all of the Himalayan mountains. Fatalities have mostly been due to injuries sustained in falls, and these have been greatly reduced by the introduction of a registration and screening system for climbers in 1995. However, Denali should never be climbed casually or taken for granted - as recently as 1967, 7 climbers were killed in a storm near the summit.

"The fact that the West Buttress route is not technically difficult should not obscure the need to plan for extreme survival situations. Of course, some climbers manage to get up and down in perfectly nice, but rare period of weather; when back home, they encourage others to climb this 'easy walkup' of a mountain. Little do they realize that it was only by sheer luck they weren't trying to keep their tent up in the middle of the night in a 60mph wind at 40° below zero, with boots on and ice axe ready in case the tent suddenly imploded."
— Peter H. Hackett, M.D., from Surviving Denali by Jonathan Waterman

The above statistics only apply to the relatively mild climbing months of the summer season. In winter, from November to April, Denali becomes one of the harshest and most extreme environments on the planet, presenting massive dangers to even the most experienced of climbers. The wind can reach 100mph or more when the jet stream descends the sides of the mountain and funnels through Denali Pass and other narrow areas at a truly freakish speed. Add to this the fact that temperatures range from -30F to -70F and it's no surprise that many people have been killed trying to climb Denali in winter.

References and Further Reading:
The Story of McKinley:
Fatality Statistics:
Denali National Park: