One of the three top-tier horses, along with the Hungarian Half-bred and the Kentucky Saddler. The American Standardbred is the fastest horse in the game. Its health and stamina are weaker by comparison, however. They are dark brown(almost solid black) with a full black mane and tail.
A deed for this horse can be purchased at any general store for $1500 ($750 with high enough honor, or low enough honor at Thieves' Landing), but only after the player has successfully broken the horse at least once.
When galloping, the player should tap A/X at a delayed rhythm - about once every second (or three strides). Doing this allows the horse to regain stamina before it is spurred again, while still retaining its top speed. Using this method, the horse can literally be spurred indefinitely, making the increased stamina of the Kentucky Saddler and Hungarian Half-Bred a useless perk.
The in-game breed is based on the real world Standardbred. See the linked article for information about the real world equivalent.
When looking for the Standardbred, it is often easy to confuse this breed with the Dutch Warmblood, which in reality is dark brown and black. The Standardbred is completely black in any lighting, and does not have any shade of brown.
A possible rare glitch spawns a herd of 4-5 Standardbreds near the river north of Beecher's Hope, close to the Great Plains/Tall Trees border. There is also a spawn point just south of Bearclaw Camp, near the river.
Oddly, there is a slightly increased chance to find it at night.
The American Standardbred is the fastest horse in the game, aside from DLC packs.
Although its the fastest horse, it has average stamina and health. So the horse is the second best, after the war horse.