During World War II, 1,711 North graduates served in the United States military; 77 did not make it home. By 1945 the school's attendance doubled. In the late 1940s, the building was expanded to accommodate huge growth in the population of North Omaha. A music wing, cafeteria, gymnasium and more classrooms were added. The swimming pool was converted into a freshman study hall and library. In the late 1950s, the late E. E. McMillan was honored as the namesake of the nearby middle school, McMillan Magnet Center.