The Tennessee Walking Horse was named the official state horse in 2000. Tennessee wallkers are one of the smoothest riding horses in the world. They have 3 smooth, natural gaits: the flat-foot walk, the running walk, and the canter,

Also known for sure footing and calm temperament , the Tennessee walking horse is the first breed of horse to bear a state name. Tennessee walkers were developed by farmers in the Tennessee bluegrass region combining the genes of thoroughbreds, Canadian pacers, saddlebreds, morgans, American standardbreds, and Narranganett pacers.

Quote from Tennessee Walking Horse: Gaited Horses:

"...A Tennessee Walking Horse will nod its head in rhythm with the cadence of its feet. Walking Horses are born with the ability to do other gaits in addition to the running walk. Some of these gaits are the rack, pace, foxtrot, stepping pace, single-foot and other variations of the famous running walk. The Tennessee Walking Horse is also famous for their "rocking chair" canter, which is a collected gallop. The canter is performed in much the same way as other breeds, but the walking horse seems to have a more relaxed way of performing this gait..."

Tennesee walking horses come in all colors and patterns - black, bay, chestnut, palomino, buckskin roan and spotted patterns.

Excerpt from Tennessee Walking Horse Home Page:

"...the Tennessee walker gained wide popularity for its ease of gait and ability to stride faultlessly over hills and ...valleys of the rocky middle Tennessee terrain...used as a utility animal for all type of farm work, as well as family transportation and recreation, the old plantation-type horse was not trained for showing in those days -- its gait was naturally inherited..."

Horses are official state symbols in 12 states:

Vermont and Massachusetts (morgan horse); Alabama (racking horse); Idaho (Apaloosa horse); Kentucky and Maryland (thoroughbred horse); Tennessee (Tennessee walking horse); North Dakota (Nokota horse); Missouri (fox trotting horse), North Carolina (colonial Spanish mustang), Florida (Florida cracker horse), and New Jersey ("the horse").

Source:

State Symbols: Tennessee Dept. of State
Tennessee Walking Horse: Gaited Horses

Links:

State Animals - Mammals: 50 States List