Southwestern Conference (Illinois)
The Southwestern Conference is a high school conference in the St. Louis Metro East area. The conference participates in athletics and activities in the IHSA Illinois High School Association. The conference comprises large public high schools in the Metro East region of suburban St. Louis.
Current Membership
The current group of schools have been together since O'Fallon joined in 2000. In 2018-19, Granite City will leave the conference for all sports while Collinsville will leave for only football.| School | Location | Mascot | Colors | 2019-20 Enrollment | IHSA Classes 2/3/4 | IHSA Music Class | IHSA Football Class | IHSA Cheerleading Class |
| Alton High School | Alton, IL | Redbirds | Red, Gray | 2,008 | AA/3A/4A | AA | 7A | Large squad |
| Belleville East High School | Belleville, IL | Lancers | Columbia Blue, Navy Blue | 2,518 | AA/3A/4A | AA | 8A | Large squad |
| Belleville West High School | Belleville, IL | Maroons | Maroon, White | 2,112 | AA/3A/4A | AA | 7A | Large squad |
| Collinsville High School | Collinsville, IL | Kahoks | Purple, White | 1,905 | AA/3A/4A | AA | 7A | Large squad |
| East St. Louis Senior High School | East St. Louis, IL | Flyers/ Flyerettes | Orange, Blue | 1,262 | AA/3A/4A | AA | 6A* | Large squad |
| Edwardsville High School | Edwardsville, IL | Tigers | Orange, Black | 2,365 | AA/3A/4A | AA | 8A | Large squad |
| Granite City High School | Granite City, IL | Warriors | Red, Black, White | 1,809 | AA/3A/4A | AA | 7A | Large squad |
| O'Fallon High School | O'Fallon, Illinois | Panthers | Blue, Gold | 2,408 | AA/3A/4A | AA | 8A | Large squad |
Sources:IHSA Conferences, IHSA Coop Teams, and IHSA Member Schools Directory
- East St. Louis would normally fall into 6A, but elects to play up one class and thus competes in 7A.