The Standardbred Horse is a relatively young breed just over 200 years old. Its origin dates from the England of the late 1700s, and specifically to a horse named "Mambrino." Mambrino had been a legend in 18th century England Trotting races for many years and was the sire of "Messenger" — an English Thoroughbred — credited with becoming the American ancestor of the Standardbred breed.
"Messenger" was brought to the United States in 1788 and later was owned by Henry Astor, brother of John Jacob Astor. For 20 years Messenger produced many of the greatest American racehorses in the stud farms of New Jersey, Pennsylvania, and New York. The famous "Man O'War" was one of his descendants. He is credited with being the horse to whom every Standardbred horse is related. Messenger's great-grandson, "Hambletonian," was foaled in 1849 in upstate New York, and soon became one of the fastest trotting horses of his time. It has been estimated that more than 90% of Standardbred horses today are related to him.
The term "Standardbred" was introduced in 1879 to distinguish those trotting horses who met a certain "standard" for the mile distance. The current standard for 2-yr olds is 2.20 minutes, and for 3-yr olds, the standard is 2.15 minutes. The standard distance is always one mile. It is interesting to remember that this breed of horses has been able to achieve this standard with some level of consistency. It appears that "Messenger" passed on some very fast genes!
More detailed descriptions of the Standardbred horse breed can be found at:
The National Museum of the Horse at Lexington, Kentucky.
Other sites of interest regarding the history of the Standardbred horse:
Standardbred Racehorse History