When the first jockstrap was invented
The ubiquitous jockstrap was invented in 1874 by Bike Athletic., and they are also often (incorrectly) credited with the invention of the athletic cup as well.
Yes, they made millions of them and had patents on many, but they were nowhere near first.
History records fighters and boxers wearing types of groin “shields” that were somewhat in a “cup shape”. Leather “inserts” dating back to the beginning of boxing may have been in that shape but pictures are elusive.
Polite society didn't discuss such things, of course, and there are few published descriptions or accounts of groin protection until well into the 1900’s.
The first patented athletic cup
One of the first recorded US patents of a modern athletic cup was in 1931 by Forrest M Record. A note of interest, the year prior to a patent for a ‘Blow distributing athletic protector” was issued by James P Taylor. It was inflated with air using a stem just like a tire. Very creative, but inflating it for sports would have been a challenge then, and it was never manufactured.
Claude Berry first to wear a steel cup
However baseball catcher Claude Berry is reported to have worn a steel “Safety Cup” around 1904, and it survives to this day. Not surprisingly hockey players also started wearing cups very early.
So it’s actual invention date is likely lost to time, and even Wikipedia is mute on the topic. The cup was an invention that slowly evolved over time out of the specific need.
Up until about 1950 athletic cups really didn’t resemble what we would call “a cup” today. They were crude, one-size-fits-all devices that would have been terribly uncomfortable, and designed largely by trial and error.
Even into the 1960’s and 1970’s the materials used to make cups were not reliable. Former Cincinnati Reds catcher Johnny Bench is reported to have broken seven cups during his Hall of Fame career. But he remained intact.
But by the late 1970’s things changed rapidly.
Sports Injury Researcher, United States