A horse can maintain a full-speed gallop for a few miles. Two to 3 miles is about the maximum distance for which even a well-conditioned horse can maintain a top speed. Horses can, however, cover very long distances at slower speeds.
The Pony Express averaged 9 to 10 miles per hour over 15- to 25-mile stages, changing horses between stages. Many very long-distance rides, called endurance rides, have been completed on horses, in which the horse has to cover 100 miles in less than 24 hours. In the Middle East 26-mile races on horseback can be completed in around an hour.