Commonwealth Games
Sporting contests were held in Olympia,the sanctuary in the W.Peloponnese,ancient Greece as a sacred truce every four years in Greece.
You have the world cup, the U.S president is elected, the Olympics are held , and so is the Euro cup. This all happens every four years.
Leap year
29th of February only happens in a leap year. So it only happens every 4 years.
If you mean the number of team members, It would be the USA Summer Olympic Team every four years.
eclipse
The Olympics is know as the biggest sporting event in the world and is held every four years in a different country. The gymnaestrada is also held every four years in a different country around the world. There are around 12,000 athletes in the Olympics but there are over 20,000 gymnasts in the gymnaestrada making it the biggest sporting event in the world for participants.
Some things that happen once every four years include: - Leap Years - US Elections - The Olympics
The President of The United States of America is inaugurated.
The Olympics are held once every fourth year.
a leap year