Most radio call signs are essentially random letters assigned by regulators. KTSM-FM, the station behind Sunny 99.9 in El Paso, is one of the exceptions. Those four letters were chosen to describe exactly where the station sits: at the meeting point of Texas, New Mexico and the Mexican state of Chihuahua.
Tri-State Media, By Design
KTSM-FM signed on June 18, 1962, as the FM sister to KTSM 1380 AM, and the call letters stand for "Tri-State Media," a direct reference to the three regions the station's signal was built to serve, according to a history of the station. El Paso sits at one of the few genuinely tri-jurisdictional points in North America, close enough to New Mexico and across the river from Chihuahua that a station naming itself after all three wasn't a marketing flourish. It was just accurate.
Beautiful Music for an Aging Audience
The station's earliest format had nothing to do with what plays on 99.9 today. KTSM-FM launched as a "beautiful music" outlet, instrumental versions of popular songs with little talk and almost no news, a format built to run quietly in the background of offices and living rooms. As that format's core audience aged, programmers gradually worked softer vocal tracks from the Top 40 into the mix to avoid losing younger listeners entirely.
A Satellite Feed Called Format 41
By 1990, the instrumental era was over. KTSM-FM had shifted completely to soft adult contemporary, running on "Format 41," a satellite-delivered soft AC service supplied by Transtar Radio Networks, a common arrangement at the time for stations that wanted a consistent national playlist without building out a full local music department.
From Clear Channel to iHeartMedia
Ownership changed hands in 1998, when San Antonio-based Clear Channel Communications bought KTSM-FM along with sister stations KHEY-FM and KHEY AM. Clear Channel pushed the playlist toward a faster, more mainstream adult contemporary sound, moving away from the softer format Transtar had supplied. When Clear Channel rebranded itself as iHeartMedia in 2014, KTSM-FM came along under that new corporate name, arriving eventually at its current identity as Sunny 99.9.
A Call Sign That Still Makes Sense
Format and ownership have both changed multiple times since 1962, but the call letters never needed updating. KTSM-FM still broadcasts into the same tri-state, tri-national footprint the name was built to describe, playing today's adult contemporary hits into a stretch of desert where three jurisdictions meet in a way few American radio markets can claim.