States: Illinois: Lake
At the time that your father attended high school in Waukegan the school was named Waukegan Township High School. It is located on Washington Street. The city later added another building, and eventually the schools split into two campuses, Waukegan East and West. As the school-aged population decreased, East was combined with West and the East your Dad's) building, shut down. It is now open again, I think as a freshman building. Actually, the building he would have used is likely the small one in the back that now has an auditorium and some rooms still.
I am not certain about school records from that time, but some local libraries or historical societies might have high school yearbooks from that time or a picture of the school.