June 6 — same day every year
Yo-yos date back at least as far as ancient Greece. A Greek vase painting from 500 BC shows a boy playing with a yo-yo.
Yo-yos were made popular in America when Donald F. Duncan manufactured the Duncan Yo-Yo in the early 1900s.
Duncan Yo-Yos are on display in the National Toy Hall of Fame, Rochester, New York and the National Yo-Yo Museum, Chico, California.
Social media hash tag: #NationalYo-YoDay
National Yo-Yo Day is celebrated on June 6 as it’s the birthdate of Donald Duncan. Born June 6, 1892, Kansas City, Missouri. Died May 15, 1971 Palm Springs, California.
So far as we are aware, no one knows who created this day as a “national day.”