The WAC grew to eight members in 1967, when Colorado State University and the University of Texas at El Paso (UTEP) joined. However, in the 1970s, massive population growth in Arizona led to the two Arizona schools dominating the conference, especially in football. Arizona and Arizona State left for the Pacific-8 Conference in 1978, which then became the Pacific-10 (now the Pacific-12). The WAC reloaded by adding San Diego State University in 1978, the University of Hawaiʻi at Mānoa (Hawaiʻi) in 1979, and the United States Air Force Academy (Air Force) in 1980. This nine-team lineup defined the WAC for the next 15 years.