The franchise can be traced back to 1939 when the Niagara Falls Rainbows were established and played as a charter member of the Pennsylvania–Ontario–New York League.
The team played in the Middle Atlantic League as an affiliate of the Philadelphia Athletics in 1946 and 1947.
Finally, the city fielded the Niagara Falls Citizens in 1950 to continue play in the Middle Atlantic League.
In 1951 the Citizens won the league's final title, before disbanding.
Each of the Niagara Falls teams played their home games at Sal Maglie Stadium.