In 1977, Columbus and Lake Mills left to join the Capitol Conference and Oregon left to join the Badger Conference. They were replaced by two schools from the Badger Conference (Edgerton and Jefferson) and one from the State Line League (Brodhead).[3] That same year, the Central Suburban Conference changed its name to the Rock Valley Conference, both a reference to the old Rock Valley League and the revised catchment area.[4] In 1982, Jefferson and Milton both left the Rock Valley to join the Southern Lakes Conference and were replaced by Beloit Catholic (from the IHSA'sTrailblazer Conference)[5] and Big Foot (formerly of the Southern Lakes).[6]Palmyra-Eagle joined the conference in 1990 to bring membership up to nine schools.[7] Beloit Catholic left to join the Indian Trails Conference in 1996[8][9] for its last few years before it closed in 2000.[10]
Membership remained unchanged until 2008 when the conference added four schools.[11] Jefferson made its return from the Southern Lakes Conference, and three newcomers joined: two from the Southern Lakes (East Troy and Whitewater) and one from the Badger Conference (McFarland).[12] The conference also split its membership into North and South Divisions:
North Division
South Division
East Troy
Big Foot
Edgerton
Brodhead
Evansville
Clinton
Jefferson
Palmyra-Eagle
McFarland
Parkview
Whitewater
Turner
This alignment lasted until 2017, when both Palmyra-Eagle and Parkview left the Rock Valley to join more similarly-sized schools in the Trailways Conference.[13] McFarland and Monroe swapped conference affiliations in 2023, with Monroe joining the Rock Valley and McFarland taking their place in the Badger Conference.[14]Delavan-Darien was also welcomed into the Rock Valley from the Southern Lakes Conference that year,[15][16] and the conference subdivided into "Rock" and "Valley" Divisions:
Rock Division
Valley Division
Big Foot
Delavan-Darien
Brodhead
East Troy
Clinton
Jefferson
Edgerton
Monroe
Evansville
Whitewater
Turner
This alignment will remain in place until the end of the 2024-25 school year, when four schools leave the Rock Valley Conference. Clinton, Jefferson and Whitewater will be joining the Capitol Conference, while Brodhead is joining a conference yet to be named with seven schools leaving the Capitol Conference (Belleville, Cambridge, Marshall, New Glarus, Poynette, Waterloo and Wisconsin Heights).[17]
