St. Charles High School began as a two-year high school in 1899, expanding to a four-year program in 1902. Originally located at Fourth and Jefferson Streets, it is situated at the former home of the St. Charles Military Academy, to which it moved after a fire in 1918. The campus began with one building in 1923 and had expanded to four by the 1965–66 school year. Within a decade, overcrowding led to the division of the district into two high schools. After a fire in 1995 destroyed all but the oldest section of the building, which was a brick construction, the school was renovated.[3]
On March 10, 2010, President Barack Obama made a visit to St. Charles and gave a speech at St. Charles High school, in the older gym on the campus. His speech dealt primarily with the proposed health care reform legislation, and while access to the speech was by invitation only, hundreds of supporters and opponents of the president were outside to witness the historic event.