BRONCO 12U™ LEAGUE was started in 1961 in order to give athletes, ages 11-12, the opportunity to play baseball or softball. The first ever Bronco World Series was held the same year in Washington, Pennsylvania between Oak Park, Illinois and Maywood, New Jersey with Oak Park winning both games by the scores of 7-5 and 10-3.

The following year, the World Series was expanded to four teams and was hosted in Rockford, Illinois. The World Series eventually grew to six teams in 1969, and the first international team was added the following year with Cantano, Puerto Rico, who ended up winning the 1970 Bronco World Series.

In 1971, the World Series was expanded to eight teams. This experiment led to a 10-team World Series in 1974, before going back to a six-team format the following year. In 1978, the World Series again expanded to eight teams, before expanding to 10 again in 2008. Finally, the Bronco World Series went back to eight in 2014 and has stayed there ever since.

The location of the Bronco World Series has changed throughout the years. It did return to PONY Headquarters in Washington, Pennsylvania in 1974 and was also hosted there in 1975 and 1977. There have been 17 different locations, with Laredo, Texas making 18, to host the Bronco World Series, including one international site as in 1973 the World Series went down south to Mexico City, Mexico. Notably, the World Series has been hosted in California a record 33 times during the years 1971, 1985-2012, and 2014-2018.