Bloomfield played concurrently in the SWIAC and Blue Chip Conference from 1968 to 1985.
Clay City and Shakamak were both concurrently in the SWIAC and TRC from joining the SWIAC until the TRC's demise in 2010. Linton-Stockton joined the TRC in 1991 while playing simultaneously in both leagues until 2010.
Loogootee and Shoals played concurrently in the SWIAC and MCC 1939–43.
Shoals played concurrently in the SWIAC and Lost River Conference from 1971 to 1974, and in the SWIAC and BCC from 1977 to 1979.
Union played in the SWIAC and TRC concurrently from 1974 to 2010.
Union was closed as a public school in 2014, however, a charter school was formed the same year carrying the history of the school. The new Union played as a non-IHSAA independent until 2018, when it joined the Southern Roads Conference.