FROM 9ZAF TO YOUR PHONE
Colorado Radio History
If you grew up in Colorado, there’s a good chance a radio voice got you out of bed, kept you company on I-25 or told you school was cancelled. This is the story of where those voices came from — a hundred-plus years of stations, DJs, call letters and format flips, from Denver to Grand Junction, Colorado Springs, Pueblo and every small town with a tower.
The 1920s: a Denver dentist and a brand-new idea
Colorado radio starts with Dr. William D. “Doc” Reynolds, a Denver dentist who ran amateur station 9ZAF out of his house on South University around 1920. He played music, read the news and basically invented local radio for his neighbors before anybody called it that. His station became KLZ, Colorado’s oldest continuously licensed commercial station. Denver picked up KFEL in 1923, and KOA arrived in 1924 with a signal big enough to reach half the country at night. Down south, Colorado Springs had stations like KFUM (the roots of KVOR), and Pueblo got KGHF in 1928.
The ’30s and ’40s: networks, news and the big AM signals
Through the Depression and the war years, radio was the living room. Colorado stations carried NBC, CBS and Mutual network shows, but they also built their own: farm reports, local news, live bands and community talent shows. Smaller towns like Trinidad, Alamosa, Durango, La Junta and Greeley got stations of their own, and the 1941 frequency shuffle moved much of the state’s dial around overnight.
The ’50s through the ’70s: Top 40 and the DJ as a star
When TV took the dramas and variety shows, radio reinvented itself around records and personalities. Denver’s KIMN became the Top 40 powerhouse a whole generation grew up with, and stations like KDZA in Pueblo and KPIK in Colorado Springs brought the same energy to their towns. The DJs became local celebrities — the people you heard at the record hop, the car dealership remote and the county fair. You can meet hundreds of them on the People page.
The FM takeover
FM was around for years before anyone cared — classical stations like KVOD, college stations like KRCC at Colorado College and KUNC in Greeley. Then in the late ’60s and ’70s, rock fans discovered the better sound, and FM took over. Boulder’s KBCO, KBPI, KTCL and a wave of rock, country and adult stations pulled listeners off AM for good. AM legends like KOA and KHOW moved toward news, talk and sports.
Consolidation and today
After the 1996 Telecommunications Act let companies own a lot more stations per market, Colorado’s dial changed hands fast. Many of the big names you grew up with now sit under a handful of owners, and plenty of local shows were replaced by syndication and voice-tracking. But local radio’s still here — and the people who made it what it was deserve to be remembered.
Dig in
- The Colorado radio timeline — every sign-on, call change and format flip we’ve found, year by year
- Stations — histories of the call letters you remember
- People — the DJs, newspeople, engineers and owners behind the mic
- By region: Denver · Colorado Springs · Southern Colorado · Northern Colorado · Western Slope · Mountain Communities
- Airchecks & video, photos, documents and memorabilia
Got a piece of Colorado radio history? An old aircheck, a station photo, a T-shirt in the closet — add it to the archive →