The first recorded attempt to conquer a rushing river was in 1811, when unprepared daredevils tried to navigate the Snake River. Because of their experience, the Snake River was nicknamed the "Mad River," a nickname that it is still fondly known by today.
The first known rubber raft, four tubes and a wraparound floor, was made by Lieutenant John Fremont and inventor Horace H. Day.
Freemont wrote about their first known whitewater raft adventure— surveying the Platte River for the US Navy— in an 1842 journal entry.
About 100 years later, whitewater rafting showed its first signs of becoming a recreational activity. The first family of whitewater rafting enthusiasts were the Smiths of Salmon, Idaho. The father, Clyde, and his sons Jacks and Don, were the first group to go on a commercial whitewater river trip, led by a veteran river man on June 9, 1940 on their native Salmon River. Later, the men became known as "the west's most capable white-water river men," and became famous for their expeditions through unchartered waters in the west.
As the Rockefellers tended to do, they provided the push that whitewater rafting needed to become a popular commercial activity. John D. Rockefeller, Jr. found a way to repurpose surplus WWII rafts, using them to take guests at his Jackson Lake Lodge on boating trips down the Snake River in the 1950’s.
It is unclear exactly who opened the first true whitewater rafting company, as the sport gained so much popularity so quickly in the 1960’s— so much so that a form of the sport, kayak slalom, was incorporated into the 1972 Munich Olympics!
The rest, as they say, is history!