The first Iditarod race was run in 1973, on the 100th anniversary of the purchase of Alaska by the USA from Russia. The race commemorates the "Great Race of Mercy," a real race against time to save lives threatened by disease.

In February 1925, a diphtheria epidemic threatened the isolated city of Nome, Alaska (diphtheria is a contagious and potentially deadly disease that is now rare because of childhood vaccinations). The lives of many children in Nome were threatened by this terrible disease, especially the native Inuit children, who had no previous contact with diphtheria, and therefore, no immunity to the disease. The only way available to save the children was to transport the medicine 674 miles across land from Nenana to Nome, using dog sleds. Twenty teams of mushers and over 100 dogs delivered the medicine in about 5 1/2 days. The lead dog of the final team of dogs was Balto, who became quite famous; the lead dog of the team that braved the toughest and longest part of the journey was called Togo.