The Kentucky Derby was first run at 1 1⁄2 miles (2.4 kilometres), the same distance as the Epsom Derby. The distance was changed in 1896 to its current 1 1⁄4 miles (2.0 kilometres). On May 17, 1875, in front of an estimated crowd of 10,000 people, a field of 15 three-year-old horses contested the first Derby.
The Preakness Stakes is an American flat thoroughbred horse race held on the third Saturday in May each year at Pimlico Race Course in Baltimore, Maryland. It is a Grade I race run over a distance of 9.5 furlongs (1 3⁄16 miles (1,900 m)) on dirt.
The Belmont Stakes is an American Grade I stakes Thoroughbred horse race held every June at Belmont Park in Elmont, New York. It is a 1.5-mile-long (2.4 km) horse race, open to three-year-old Thoroughbreds.