This article is from the Working Dogs FAQ, posted to rec.pets.dogs newsgroup. Maintained by Cindy Tittle Moore with numerous contributions by others.
My thanks to Stephen Lee for this section.
History
Prior to the formation of sled dog racing as a formal sport, sled dogs were bred and used by native peoples of the polar regions of the world in their everyday lives for survival in harsh climates. Two dogs commonly employed in sledding are Alaskan Malamutes and Siberian Huskies. These two breeds had quite different origins and uses. Alaskan Malamutes originated with a group of Eskimo people known as the Mahlemiut. The dogs of that time were very large freighting dogs, capable of pulling heavy weight. The Mahlemiut people inhabited the region in the upper part of the Anvik River in Alaska, and were spread out over a large area. The Mahlemiut people used these dogs for hauling food back to the villages. The gold rush in 1896 created a high demand for these dogs. On the other hand, Siberian Huskies originated with the Chuckchi people of northeastern Siberia. These people had a Stone Age culture and used their dogs for a variety of things, like herding reindeer and pulling loads. These dogs were smaller and faster than their Mahlemiut counterparts. These dogs were exported to Alaska at around the time of the gold rush. Thus the gold rush played a very important role in the development of our modern day sled dog breeds.
Sled dog racing began as a formal sport with the first All-Alaska Sweepstakes race in 1908. Prior to this, Alaska's mushers had little opportunity for recreation and they used their teams primarily for work and transportation. Rules for the races were established, and they provided a good diversion to the difficult living conditions. In the 1920's, airplanes were gradually replacing sled dog teams for transportation, freight hauling, and mail delivery. In 1925, sled dogs proved that they were invaluable during the "Great Race of Mercy to Nome." In Nome, an outbreak of diphtheria threatened to become a fatal epidemic. A 20lb package of antitoxin serum needed to be relayed from Nenana to Nome. Twenty drivers and more than 100 dogs were recruited for the run. Planes were ruled out due to extreme cold (40 below and colder) and if the plane crashed, the serum would be lost. Serum was transported from Anchorage to Nenana by train. The drive was a success, the serum was delivered and lives were saved. The drive covered some 674 miles in less than five and a half days. This, along with the simple commemoration of the uses of the Iditarod trail, is the origin of the Iditarod sled dog race.
 
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