1000 miles to go : Anchorage to Nome, Alaska. The annual Iditarod sled dog race is a reconstruction of the 1925 serum run to Nome, also known as the Great Race of Mercy The Serum Run, was anneffort, organized by the communjty transport of diphtheria antitoxin by dog sled relay across the US territory of Alaska by 20 mushers and about 150 sled dogs across 674 miles (1,085 km) in 5 1⁄2 days, saving the small town of Nome and the surrounding communities from developing edpidemic and a certain 100%