The Red Brick School operated as the sole official school building in Oswego for the next 60 years until the arrival of Caterpillar and Western Electric, who built factories north of Downtown Oswego, near Montgomery, Illinois. The opening of both factories resulted in a population boom within the village. By 1947, The Red Brick School could no longer hold full class sizes for all grades, and the village moved to build a new school for high school courses. At the beginning of the 1951-1952 school year, high school classes began at the new Oswego High School on Franklin Street. The Red Brick school served elementary and middle school classes for the next 20 years, before it was shuttered and razed to build a new post office.