The Canadian Derby is a Canadian Thoroughbred horse race run annually at the Century Mile Racetrack and Casino in Leduc County, Alberta. A Grade III event held in August, it is open to three-year-old horses and is raced on dirt over a distance of one mile and a quarter. The race was the creation of future Canadian Horse Racing Hall of Fame inductee R. James Speers and first run in 1930 at his Polo Park Racetrack in Winnipeg, Manitoba. Inaugurated as the Manitoba Stakes, it was restricted to Manitoba-bred horses until 1936 when the race was renamed the Manitoba Derby and made open to three-year-old horses bred in Canada. In 1941, the name was changed again to its present form as the Canadian Derby. In 1942, future Canadian and U.S. Racing Hall of FamejockeyJohnny Longden won this race. As the Canadian Derby grew in prestige and its purse money increased, top horses from Toronto and Montreal began coming west to compete in the race. In 1937 Goldlure won Canada's most prestigious race, the King's Plate. For owner Harry Hatch, trainer Bill Bringloe would later ship the colt 1,300 miles by rail transport from Toronto and win the Derby. Budpath, another King's Plate winner, won the 1941 edition of the Canadian Derby. However, not all eastern-based horses have fared so well. In 1942, Ten To Ace was shipped in from Toronto by leading owner/trainer Harry Giddings, Jr. The colt had won the King's Plate as well as the Prince of Wales Stakes and according to TIME magazine was being called "the greatest Canadian horse of all time." Not only was Ten To Ace defeated in the Canadian Derby, he finished dead last. In 1956, Polo Park Racetrack was closed and the race was moved to Northlands Park in Edmonton, Alberta. In 2019, the race moved to its present location at the Century Mile Racetrack and Casino south of Edmonton. The Canadian Derby was contested at 1 mile from 1930 to 1933, miles from 1934 to 1956, and miles from 1957 until 2018. The race returned to miles in 2019 when it was moved to Century Mile Racetrack. In 2017, Chief Know It All finished first but the jockey of runner-up Double Bear filed a claim of interference. When the claim was rejected by track stewards the matter was appealed to the Alberta Horse Racing Appeal Tribunal which in July of 2018 ruled in favour of the owner of Double Bear. An appeal of the Tribunal's order resulted in an August 2018Court of Queen's Bench of Alberta ruling that Chief Know It All had interfered and declared Double Bear the winner.