The Tennessee Walking Horse
The Tennessee Walking Horse or Tennessee Walker is known for its unique four-beat "running walk" and flashy movement. It was originally developed in the Southern United States for use on farms and plantations, where coving ground quickly and comfortably was desired. It is a popular riding horse due to its calm disposition, smooth gaits and sure-footedness. The Tennessee Walking Horse is often seen in the show ring, but also popular as a pleasure and trail riding horse using both English and Western tack. Tennessee Walkers are also seen in movies, television shows and other performances.
The breed first developed in the late 18th century when Narragansett Pacers and Canadian Pacers from the eastern United States crossed with gaited Spanish Mustangs from Texas. Many of the same horses that were foundation TWH horses were also foundation horses in the Missouri Foxtrotting Horse Breed as well as some other gaited breeds. Other breeds were later added, and in 1886 a foal named Black Allen, now considered one of the main foundation sires of the breed, was born. In 1935 the Tennessee Walking Horse Breeders' Association was formed, and the studbook closed in 1947, not allowing any more new horses to be registered. In 1939, the first Tennessee Walking Horse National Celebration was held, an annual event that in recent years has attracted considerable attention and controversy.
The two basic categories of Tennessee Walking Horse show competition are called "flat shod" and "performance", differentiated by desired leg action. Flat shod horses, wearing regular horseshoes, exhibit more natural and less exaggerated movement, while performance horses wear built-up pads or "stacks" along with other weighted action devices, creating the so-called "Big Lick" style.
(For more information about things mentioned here visit this link: http://en.wikipedia.org/wiki/Tennessee_Walking_Horse)
Here's a Slow Motion Video of a Modern Performance "Big Lick" Running Walk &
Then a Video of a Foundation "Flat Shod" Style Running Walk:
Both of the above horses are correctly performing The Running Walk gait (by the front shoulders trotting and the rear end walking), but the show horse is animated in a rough gait and the "flat shod" trail type horse is doing a smooth gait that is comfortable to ride, and not harmful to the horse.
Tennessee Walkers also come in many colors...see some examples below: