Used by native hunters, then by Russian explores, and then by 20th century gold seekers, the Iditarod trail in Alaska is not a single trail, but rather a network of 2,300 miles of trails. The trail begins in a town called Steward, 50 miles north of what eventually became the Alaska Railroad, and ends 1,150 miles later in the town of Nome. In 1925, a diphtheria epidemic threatened the population of Nome. The desperately needed serum was raced from Nenana to Nome by sled dog teams along this trail. The 20 mushers covered almost 700 miles in little more than 127 hours (about six days) in temperatures that rarely rose above -40 degrees. The serum arrived in time to prevent the epidemic, saving hundreds of lives. Each year this remarkable feat is commemorated with a dogsled race from Anchorage to Nome. Congress designated this trail as a historic trail in 1978.