According to former Ironman Champion, triathlon historian and author, Scott Tinley, the Triathlon is anecdotally based on a race in France during the 1920-1930s that was called "Les trois sports", "La Course des Débrouillards" and "La course des Touche à Tout". Nowadays, this race is held every year in France near Joinville le Pont, in Meulan and Poissy. In 1920 the French newspaper "L´Auto" reported on a competition called "Les Trois Sports" with a 3 km run, 12 km bike and a crossing of the channel Marne. Those three parts were done without any break. There are articles in French newspapers about a race in Marseille in 1927. There is a 1934 article about "Les Trois Sports" (the three sports) at the city of Rochelle about a race with three components: (1) a channel crossing (c. 200 m), (2) a bike competition (10 km) around the harbor of Rochelle and the parc Laleu, and (3) a run (1200 m) in the stadium André-Barbeau. Since the 1930s, very little was heard about triathlon until 1974 at San Diego's Mission Bay in Southern California, where a group of friends began training together. This occurrence is well-documented and has no basis on the old French event. Amongst them were runners, swimmers and cyclists and before long training sessions turned into informal races. Directed and conceived by Jack Johnstone and Don Shanahan, the first Mission Bay Triathlon was held on September 25th 1974 and welcomed 46 athletes. This date is celebrated as the day modern triathlon began.
The first modern long-distance triathlon event (2.4 mile (3.86 kilometer) swim, 112 mi (180.2 km) bike ride, and a 26.2 mi (42.2 km) run) was the Hawaiian Iron Man Triathlon, the idea for which arose during the awards ceremony for the 1977 Oahu Perimeter Relay (a running race for 5-person teams). Among the participants were numerous representatives of both the Mid-Pacific Road Runners and the Waikiki Swim Club, whose members had long been debating which athletes were more fit, runners or swimmers. On this occasion, U.S. Navy Commander John Collins pointed out that a recent article in Sports Illustrated magazine had declared that Eddy Merckx, the great Belgian cyclist, had the highest recorded "maximum oxygen uptake" of any athlete ever measured, so perhaps cyclists were more fit than anyone. Cdr. Collins and his wife, Judy, had taken part in the triathlons staged in 1974 and 1975 by the San Diego Track Club in and around Mission Bay, California, as well as the Optimist Sports Fiesta Triathlon in Coronado, California, in 1975. A number of the other military athletes in attendance were also familiar with the San Diego races, so they understood the concept when Cdr. Collins suggested that the debate should be settled through a race combining the three existing long-distance competitions already on the island: the Waikiki Roughwater Swim (2.4 mi./3.862 km), the Around-Oahu Bike Race (115 miles; originally a two-day event) and the Honolulu Marathon (26.219 mi./42.195 km). It is worth noting that no one present had ever done the bike race and they did not realize it was a two-day, not one-day, event; Cdr. Collins calculated that, by shaving 3 miles off the course and riding counter-clockwise around the island, the bike leg could start at the finish of the Waikiki Rough Water and end at the Aloha Tower, the traditional start of the Honolulu Marathon. Prior to racing, each athlete received three sheets of paper listing a few rules and a course description. Handwritten on the last page was this exhortation: “SWIM 2.4 MILES! BIKE 112 MILES! RUN 26.2 MILES! BRAG FOR THE REST OF YOUR LIFE!” With a nod to a local runner who was notorious for his demanding workouts, Collins said, "Whoever finishes first, we'll call him the Iron Man." Of the fifteen men to start off the in early morning on February 18th, 1978, twelve completed the race and the world's first IRONMAN, Gordon Haller, completed in 11 hours, 46 minutes, and 58 seconds..
Today, a number of triathlon events over varying distances are held around the world. The standard "Olympic Distance" of 1.5/40/10k was created by long time triathlon race director, Jim Curl in the mid 80's after he and partner, Carl Thomas, successfully produced the U.S. Triathlon Series between 1982 and 1997. USTS, as it was known, did more to bring accessible triathlons to the masses than any other group. The Hawaii Ironman Triathlon now serves as the Ironman world championship, but the entity that owns the race, the World Triathlon Corporation, hosts other triathlons around the world that are also called Ironmans. Long-distance multi-sport events organized by groups other than the World Triathlon Corporation may not officially be called "Ironman" races. Such triathlons may be described as "Iron-distance" or "Half-Ironman", but the "Ironman" label is the official property of the World Triathlon Corporation.
The International Triathlon Union (ITU) was founded in 1989 as the international governing body of the sport, with the chief goal of putting triathlon on the Olympic program. The ITU has never officially sanctioned the Ironman Triathlon. Some believe that the Hawaii Ironman should be recognized as the official world championship for the sport as a whole, and as such should be sanctioned by the ITU. For its part, however, the ITU has expressed little interest in supporting longer distance triathlon, choosing to retain its focus instead on the shorter races geared toward the Olympics. The sport made its debut on the Olympic program at the Sydney Games in 2000 over the Olympic Distance (1500 m swim - 40 km bike - 10 km run). Since its founding, triathlon has grown significantly and now includes thousands of races with hundreds of thousands of competitors worldwide each year. The history of the sport is documented in Scott Tinley's book, "Triathlon: A Personal History" (Velo Press, 2002).