 Because each race is very long, trails of natural terrain are generally used.Contemporary organized endurance racing began in California around 1955, and the first race marked the beginning of the Tevis Cup This race was a one-hundred-mile, one-day-long ride starting in Squaw Valley, Placer County, and ending in Auburn.Founded in 1972, the American Endurance Ride Conference was the United States' first national endurance riding association.