This is a list of former high school athletic conferences in the Southwest Region of Ohio, as designated by the OHSAA. If a conference had members that span multiple regions, the conference is placed in the article of the region most of its former members hail from. Because the names of localities and their corresponding high schools do not always match and because there is often a possibility of ambiguity with respect to either the name of a locality or the name of a high school, the following table gives both in every case, with the locality name first, in plain type, and the high school name second in boldface type. The school's team nickname is given last.
The BCL was one of the local small-school county leagues in Southwest Ohio. Consolidation reduced the number of teams to five by 1967, and in 1970 these five joined with the Adams and Highland county leagues to form the Southern Hills Athletic League.
The Interscholastic Athletic Association was founded March 23, 1896, and continued for several years with both public and private high schools until 1931, when it rebranded itself as the Public High School League. Now encompassing solely the public high schools in Cincinnati, the league lasted until 1985, when reshuffling of city and suburban Cincinnati high schools took place, which led to the formation of the Cincinnati Hills League, Eastern Metro Conference, Metro County Conference, and Western Metro Conference.
This small-school county league is another that hosted members from outside their borders. In this case, Harveysburg from Warren County joined a few years before the conference ended, as the school would merge with three Clinton County schools to become Clinton-Massie. The school would actually be based in Harveysburg until a new school was built near Clarksville, in Clinton County. Blanchester was not included in the 1959–60 standings, due to growing to a AA-sized school by annexing Jefferson, but were allowed back into league play the following season. Blanchester and Clinton-Massie would concurrently play in the CCL and Fort Ancient Valley Conference for the 1964–65 school year, after which the other two CCL schools consolidated into East Clinton, who would join the FAVC nine years later.
One of the short-lived conferences resulting from realignment in the Cincinnati area, the league merged into the Queen City Conference superconference in 1989.
The DVL was formed in 1956, as the Madison County League was reduced through consolidation from nine schools to four over a two year period, forcing the schools to seek other schools to compete with. Growing from its five initial schools, the conference grew to 11 schools by 1963, but never achieved any sense of stability, as schools joined and left for other conferences throughout its existence. The conference folded in 1977, as five of its members left for other leagues at the same time.