The Central Suburban League is an IHSA-recognized high school extracurricular conference comprising 12 public schools located in the North Shore suburbs of Chicago. Comprising 12 relatively large high schools, it is among the larger high school conferences (by student population) in Illinois. Schools Former schools Niles East High School: Opened in 1938, the school was Niles High School until 1959 when Niles West opened. The school closed in 1980. Maine North High School: Opened in 1970, the building closed in 1981. New Trier West High School: New Trier was split into a west and east campus in 1967. Between 1967 and 1981 the west campus was a normal high school of its own. In 1981, due to a decline in the school's population, the west campus was turned into a freshman only campus (1981-1985). The west campus closed in 1985. Once again in 2001, District 203 decided to open it as a freshman campus. It still operates, and is known as the Northfield Campus. Waukegan West High School: Between 1975 and 1990, Waukegan split into a west and east campus. Starting in 1990, the west campus folded into the east campus. Waukegan High School: Waukegan, members of the CSL between 1975 and 2016, left the conference after 41 seasons to join the revamped North Suburban Conference. Waukegan competed in the CSL South while in the conference. Divisional alignment While the divisions' names are geographic, their makeup is not based on a school's location. The North Division includes the schools with the smaller enrollments while the South Division includes the schools with the larger enrollments. Every two years the member school's official enrollment is used to determine division alignment. Not all activities and sports make use of the division alignment. In chess, teams compete as a part of the North Suburban Chess League which comprises schools from many conferences. Scholastic Bowl plays as a single twelve team league. Niles North moved to the CSL South for the 2016-'17 season after former South Division school Waukegan was replaced with Vernon Hills. Vernon Hills, which had the smallest enrollment in the conference at that point, was placed in the North Division. In the 2019-2020 season, Glenbrook North and Niles North swapped divisions because of a division realignment. History The CSL traces its history back to the founding of the Suburban League in 1913, of which Evanston and New Trier were both founding members.