Quote from the inspiring story of hero sled dog Balto and his
team's thousand mile race: Sled Dogs: an Alaskan Epic - PBS):

"In 1925, a life-or-death race to rescue the children of Nome, AK, from disease made an international hero of one sled dog - and eventually led to the creation of Alaska's Iditarod sled dog race."

From About Sled Dogs and Sled Dog Racing by Stephen R. Lee: Contrary to common belief, the word "mush" is not used to drive sled dogs. Mush comes from the French word "marche" which is from the verb "marcher" which means to walk. Undoubtedly, the French used this during gold rush days. The word "mush" is felt to be too "soft" a sound to be used as a command. Below is a short list of common commands and terms associated with dog driving sports.

Hike: Get the dogs moving

Gee: Turn right

Haw: Turn left

Easy: Slow down

Musher: One that drives sled dogs

Mushing: The act of driving sled dogs

Lead dog: Dog that steers the sled dog team and regulates speed

Wheel dog: Dogs closest to the sled

Sled: Wooden rig the dogs pull in the snow and on which you stand

Snowless rigs: Also called training carts. Take the place of the sled when there is no snow.

Nine other states recognize official canine symbols:

State Dogs: Louisiana: Catahoula Leopard Dog, Maryland: Chesapeake Bay retriever, Massachusetts: Boston terrier, Pennsylvania: great Dane, Texas: blue lacy, South Carolina: Boykin spaniel, North Carolina: Plott hound, Virginia: American fox hound, Wisconsin: American water spaniel.

Source:

Student Information - State Symbols: AK Dept. of Commerce
Hero Sled Dog Balto: Sled Dogs: An Alaskan Epic
Stephen R. Lee: About Sled Dogs and Sled Dog Racing

Links:

Making of a Sled Dog: PBS.org
Sled Dogs: An Alaskan Epic: PBS.org
Dog Mushing: Fairbanks Visitor Information
Iditarod: official site of the last great race
Working Dog Web: dog breeds, training, info
State Animals - Mammals - Cultural Symbols (50 states)