There are 16 major programming competitions
The first one started in 1970. A few of the newer ones are online only.
Most of them started or are hosted in the USA
Here is my list. You can contribute to it on GitHub.
I came across one interesting stat in my research. Gennady Korotkevich is a programmer who is currently the highest rated programmer on all 5 of the major competitive programming sites!
It would be interesting to see trends in the number of participants and prize amounts in these competitions over time. I’m curious if eSports with prizes in the millions, will sap people away from programming competitions.