Here's some info from Wikipedia (linked below)
The Iditarod Trail Sled Dog Race, usually called the "Iditarod" and known as the "Last Great Race", is an annual dog sled race in Alaska, where mushers and teams of dogs cover more than 1,000 miles (1,600 km) in less than two weeks, frequently through blizzards causing whiteout conditions, and sub-zero weather and gale-force winds which can cause the wind chill to reach −100° F (−75° C). The trail runs through the U.S. state of Alaska, from the city of Anchorage in the southeast, up the Rainy Pass of the Alaska Range into the sparsely populated Interior, and then along the shore of the Bering Sea, finally reaching Nome in the northwest. The teams cross a harsh but starkly beautiful landscape under the canopy of the Northern Lights, through tundra and spruce forests, over hills and mountain passes, and across rivers. While the start in Anchorage is in the middle of a large urban center, most of the route passes through widely-separated towns and villages, and small Athapaskan and Inuit settlements. The Iditarod is regarded as a symbolic link to the early history of the state, and has many traditions commemorating the legacy of dog mushing, most famously the diphtheria serum run of 1925 which saved the children of Nome from the "black death". The race is also associated with the spirit of "America's Last Frontier", including the traits of perseverance, testing one's own limits, and an adventuresome spirit.