As flat racing became popular with the colonists, the Quarter Horse gained even more popularity as a sprinter over courses that, by necessity, were shorter than the classic racecourses of England, and were often no more than a straight stretch of road or flat piece of open land. When matched against a Thoroughbred, local sprinters often won.  As the Thoroughbred breed became established in America, many colonial Quarter Horses were included in the original American stud books, starting a long association between the Thoroughbred breed and what would later become officially known as the "Quarter Horse", named after the 1⁄4 mile (0. 40 km) race distance at which it excelled. with some individuals being clocked at up to 55 mph.