The Alaskan Iditarod commemorates the "Great Mercy Race" of January 1925 which unfolded when Dr. Curtis Welch diagnosed several cases of diphtheria in Nome. The nearest source of serum was over 900 miles away in Anchorage. Since airplanes of the era were unsuitable to fly in Alaska's harsh winter weather, a land relay system using 20 Mushers and their dog teams was set up via radio and telephone to deliver the medication to Nome.
The serum was delivered 250 miles by train from Anchorage to Nenana where the first relay team picked up the serum and headed for Nome 674 miles west. At the same time Nome's greatest Musher, Leonhard Seppala, drove east with his best lead dog "Togo" and a team of 20 dogs. Along the way Seppala dropped dogs off at several points so he would have fresh animals on his return trip. To save time Seppala crossed the Norton Sound and met a westbound musher outside Shaktoolik.