The Standardbred (saddle type), once called the American Trotting Horse, was a product of crossbreeding among Morgan, Thoroughbred, Canadian Trotter, Narrangansett Pacer, Hackney, Arab, and Barb horses. The name Standardbred came from the ideal that these horses must trot or pace a mile under a standard time.

The Standardbred can be traced back to Messenger, a gray Thoroughbred of the Darley Arabian line. Messenger’s bloodline appears three times in the pedigree of Hambletonian 10, who was foaled in 1849. Hambletonian 10 can be traced to nearly 99 percent of all Standardbreds today.

The Standardbred resembles the Thoroughbred in body, size, and structure. It carries a medium-size neck and muscular hindquarters. Standardbreds either trot or pace a standard time to earn their registry; however, only rarely do they use this criterion. They are of solid color, with bay being predominant, and on the average stand 15.2 hands tall at the withers. Standardbreds are known for their speed and stamina while driving.