The Iditarod is a long-distance sled dog race held annually in Alaska, covering approximately 1,000 miles from Anchorage to Nome. It commemorates the historical 1925 serum run to Nome, where dog teams delivered diphtheria antitoxin to combat an outbreak. The race typically takes place in early March and features teams of mushers and their dogs, navigating through challenging terrain and harsh winter conditions. It is considered one of the toughest endurance races in the world.