KTRO-FM came into existence through a complicated deal that involved five owners of radio stations in Oregon and featured both signal downgrades and frequency migrations. It started when Salem Communications bought the FM signal from New Northwest Broadcasters in 2005, who had operated it as KAST on 92.9 in Astoria, Oregon. To make room on the Portland dial, KPDQ-FM, also owned by Salem, moved from 93.7 to 93.9 and downgraded its broadcast station class from C to C2. McKenzie River Broadcasting's KKNU-FM on 93.1 and licensed to Springfield, moved to 93.3. Bay Cities Building's KDCQ on 93.5 and licensed to Coos Bay, moved to 92.9. Meanwhile, Oregon Eagle's KTIL-FM on 94.1 and licensed to Tillamook, moved to 94.3. New Northwest's own 94.3 licensed to Long Beach, Washington/Astoria, picked up the KAST-FM callsign and format from the original 92.9 to 99.7.
Salem Communication, which normally "target[s] audiences interested in Christian and family-themed content and conservative values, brought in José Santos of Santos Latin Media, former program director of KLVE in Los Angeles, to consult on its change to a Regional Mexican format.