Freestyle skiing has its roots in Scandinavia, similar to all skiing disciplines, but its primary development occurred in North America. In the 1930s Norwegian skiers used ski acrobatics in training for cross-country and alpine competitions. It was considered an acceptable part of training but not a true competitive sport. In the United States, freestyle skiing developed as a part of professional ski exhibitions early in the 20th century. Standardized competitions began in the 1960s with the first freestyle skiing event taking place in Waterville Valley, New Hampshire in 1966. The first professional competitions were held in 1971 and the World Cup freestyle tour began in 1980. In 1979, the Fédération Internationale de Ski (FIS) recognized freestyle skiing as a discipline. The first World Championships were contested in 1986 in Tignes, France. In 1988 at Calgary, freestyle style was a demonstration sport, with all three disciplines – aerials, ballet, and moguls – demonstrated. For 1992, freestyle was advanced to a medal sport, but only moguls was conducted as a medal sport. Aerials was held at the 1992 Winter Olympics, but only as a demonstration event (as was ballet) – it would be advanced to full medal status in 1994. The competition in 1992 was held on the same course in Tignes where the first World Championships had been held.