Racing against time, 20 mushers and 150 sled dogs relayed the serum from the railroad in Nenana overland to Nome, using a river and trail system. They faced blizzards, extreme sub-zero temps, and fierce winds causing whiteout conditions, in what the world press dubbed “The Great Race of Mercy”. The relay teams traveled 674 miles in 5-1/2 days.
Temperatures during the serum run dropped to -62F and wind chills of -85F were common. Many mushers developed frostbite and several dogs died in the effort. Despite all of that, not one vile of serum broke. Within hours after arrival, the serum was thawed and ready for use.