Given a reference text on the beginnings of triathlon, tell me where the event was first held, in what year, and what sport was first in the sequence of the race.

Context: The first modern swim/bike/run event was held at Mission Bay, San Diego, California on September 25, 1974. The race was conceived and directed by two members of the San Diego Track Club, Jack Johnstone and Don Shanahan. Johnstone recalls that he was a part of the 70s jogging craze in America and that after entering a few races he was not regaining his "mediocre fitness" despite having been a member of the 1957 Collegiate and AAU All-American swim teams. Then in 1973, Johnstone learned of the Dave Pain Birthday Biathlon, a 7.2 km run followed by what was billed as a quarter-mile swim. The following year, after competing in the event for the second time and placing in the top ten, Johnstone desired more of this style of race and with equal emphasis on the swim. So he petitioned the chairman of the San Diego Track Club who told him he would add a race to the club calendar. But the rest of the race was up to Johnstone to organise, and at the same time he was to contact Don Shanahan so there wouldn't be too many "weird" races on the club schedule. Shanahan told Johnstone that he wanted to include a biking leg to the race; whilst hesitant Johnstone agreed to the addition. When naming the event the pair used the unofficially agreed naming system for multisport events, already used for pentathlon, heptathlon, and decathlon. So they used the Greek prefix tri for the number of events, followed by the already familiar athlon, hence naming the event the Mission Bay Triathlon. It is worthy of note that neither founder had heard of the French events; both believed their race was a unique idea.

On Wednesday, September 25, 1974, the race started. It began with a run of a 4.8 km loop, followed by biking twice around Fiesta Island for a total of 8.0 km. Entrants would then get off the bikes, take their shoes off and run into the water to swim to the mainland. That was followed by running in bare feet, then swimming again along the bay, then one last swim up to the entrance of Fiesta Island, and a final crawl up a steep dirt bank to finish. Most participants were not skilled swimmers, so Johnstone recruited his 13-year-old son to float on his surfboard and act as lifeguard. Some participants took longer than expected, and it began to get dark as they finished their swims. Shanahan recalls they pulled up a few cars and turned on the headlights so the athletes could see. Johnstone and Shanahan were surprised by the large number of entrants, mainly coming from local running clubs. Two notable entrants, Judy and John Collins, would four years later found the event which brought international attention to the new sport: the Hawaii Ironman.

Answer: The first triathlon occurred in San Diego, California in 1974. Unlike today's events, the triathlon began with a run.