From Ohio History Central
The toy that is now known as the Yo-Yo has probably existed for more than one thousand years. Scholars debate exactly when and where this toy originated, although a majority of historians now believe that the first known Yo-Yo probably came from China.
Scholars also debate when when the Yo-Yo arrived in the United States. The United States Patent Office granted the first patent for the Yo-Yo in the United States to Cincinnati, Ohio, residents James L. Haven and Charles Hettrich. Charles Hettrich's last name is also sometimes spelled Hittrick or Hettick, although the United States Patent Office recorded his name as Hettrich. The Patent Office granted the patent on November 20, 1866. Haven and Hettrich called their version of the Yo-Yo the whirligig.
In the United States, Pedro Flores, a Filipino immigrant, first called the toy the Yo-Yo in 1928 . Flores trademarked the term Yo-Yo, but he never owned the patent for the toy. Flores soon sold the name to the Duncan Yo-Yo Company, which manufactured approximately eighty-five percent of all Yo-Yos in the United States during the 1930s, 1940s, 1950s, and 1960s. The Duncan Yo-Yo Company eventually could manufacture sixty thousand Yo-Yos per day, and the firm sold forty-five million Yo-Yos worldwide in 1962 alone. At the start of the twentieth-first century, no single company dominates Yo-Yo production like the Duncan Yo-Yo Company did from the late 1920s to the mid 1960s.