Northwestern Conference (IHSAA) Former members Former members

| School | City | Mascot | County | Year_joined | Previous_Conference | Year_Left | Conference_Joined |
|---|---|---|---|---|---|---|---|
| East Chicago Roosevelt | East Chicago | Roughriders | 45 Lake | 1963 | Northern Indiana | 1968 | Indiana Lake Shore |
| East Chicago Washington | East Chicago | Senators | 45 Lake | 1963 | Northern Indiana | 1968 | Indiana Lake Shore |
| Gary Emerson | Gary | Tornado | 45 Lake | 1963 | Northern Indiana | 1981 | none (school closed, reopened as Emerson VPA) |
| Gary Froebel | Gary | Blue Devils | 45 Lake | 1963 | Northern Indiana | 1969 | none (school became MS, closed 1977) |
| Gary Mann | Gary | Horsemen | 45 Lake | 1963 | Northern Indiana | 2004 | none (school closed) |
| Gary Tolleston | Gary | Blue Raiders | 45 Lake | 1963 | Northern Indiana | 1969 | none (school became MS, closed 2007) |