The first triathlon took place in San Diego in 1974. It was a birthday celebration for a member of the San Diego Track Club.
Lots of the runners in that group were also comfortable in the water (surfers and lifeguards) who had some sort of bike (beach cruisers and road bikes). The course had several run and swim legs and a single bike leg that toured Mission Bay.
The next big step was the first ironman competition on Oahu in 1978. That event was the culmination of a discussion (argument?) over who was the fittest athlete the one who did the Waikiki Rough Water Swim (2.4mi), the one who did the Around The Island Bike Race (112mi) or the one
who ran the Honolulu Marathon (26.2mi). The only way to settle the discussion was to do all three in one day.
In 2000 Triathlon debuted as an Olympic sport in Sydney. There are over 150,000 USA Triathlon annual members, we’ve seen year-to-year growth of 55% and the sky is the limit.