Denali is the highest mountain in North America and perhaps the single most impressive mountain in the world--all higher peaks are in the greater Himalaya or in the Andes, part of enormous mountain ranges. Denali rises almost alone, 16,000 feet above the snowline, with only nearby Mount Foraker even close to it in height. Although part of the Alaska Range, a massive ice-clad range of spectacular peaks, Denali so utterly dominates its area that what would otherwise be major ice peaks sometimes seem like mere foothills.
Denali is also perhaps the coldest mountain in the world outside of Antarctica--its combination of great height, high latitude, and terrible weather are literally unique. The summit area is below zero degrees Fahrenheit almost all of the time, and ferocious wind lashes the peak virtually incessantly.
Although considered a technically easy climb by the most popular routes, an ascent of Denali is a serious undertaking made difficult by the cold, the weather, and the sheer scale of the massive mountain. On average during the past few years, about 1000 climbers attempt the summit per season, 500 make it, and 3 die. The climbing season runs from mid-April until mid-July, since before then it is too cold, and after that too stormy and the snow too mushy and unstable from too much sun. Theoretically, early season (May) is colder but less stormy, and later (June) is warmer with more snowfall, but in a given year anything can happen. Success percentages for a year have gone as low as 31% (1987) or as high as 67% (1983).
The standard route is the technically easy West Buttress, which starts at a glacier airplane runway at 7200'--virtually everyone flies on to the glacier to avoid an arduous approach. The standard rule is to allow three weeks for the climb, and to be prepared to spend a week of that holed up in your tent waiting for the weather to clear. Other routes include: the Muldrow Glacier route, technically easy but involving a long approach over the tundra from the north; the West Rib, a more challenging climb involving a steep couloir; and the Cassin Ridge, a committing and difficult rock climb.
On August 30, 2015, the US Department of the Interior, with the support of the US president, changed the official name of the mountain to "Denali" from "Mount McKinley". This change ratifies the name that has long been used by many in the mountain climbing community, as wells as by the Alaskan Natives. To many it had long seemed a more fitting name than one memorializing the obscure 25th U.S. president, William McKinley. The U.S. Congress changed the name of the surrounding park to Denali National Park in 1980, but congressmen from Ohio (McKinley's home state) blocked the name change for the mountain itself for many years. Although the peak was named by a partisan prospector before McKinley was even elected president, his subsequent 1901 assassination helped make the name stick.
Perhaps the best justification for naming the peak after McKinley was that he selected Theodore Roosevelt as his vice-president, and therefore his assassination put the first environment-minded president into office.