KLZ is Colorado’s oldest continuously licensed commercial broadcasting station. Its roots reach to Dr. William D. “Doc” Reynolds, a Denver dentist and radio experimenter who operated amateur station 9ZAF from his home at 1124 S. University Boulevard beginning around 1920. Reynolds and his family used the station for music, news and experimental broadcasts before federal rules created a formal broadcasting category.
On March 10, 1922, the Department of Commerce issued Reynolds Radio Company Colorado’s first broadcasting authorization under the new rules, assigning the call letters KLZ. Early KLZ programming included concerts, news, market and financial reports, children’s stories, sermons and music. Reynolds played saxophone and violin, while his wife Naomi played piano. The station later moved from the Reynolds home to the Shirley-Savoy Hotel.
Under the Federal Radio Commission’s General Order 40, KLZ moved to 560 AM on November 11, 1928, the frequency it continues to use. KLZ became an important Denver news and entertainment outlet through radio’s network era. In 1953 its lineage expanded into television with KLZ-TV, now KMGH-TV/Denver7. Time-Life acquired KLZ Radio and Television in 1954.
KLZ’s postwar programming included notable local personalities and early audience-participation programs. Its FM sister station later developed separately; KLZ-FM became KAZY in 1976. KLZ-AM has changed owners and formats through the decades while retaining the historic KLZ call letters on 560 AM.
Historical notes: First Colorado broadcasting license issued March 10, 1922; originally operated from 1124 S. University Boulevard; assigned 560 kHz in 1928.
Sources and further reading
- KLZ Radio, “About KLZ” — station account of its March 10, 1922 first license and early history.
- Broadcast Pioneers of Colorado, “Denver Radio” chronology — documents KLZ’s ownership changes, programming, newsroom, personalities, and 1950s–1970s chronology.
- Colorado State Library, Year Book of the State of Colorado (1932) — contemporary state publication identifying the March 10, 1922 KLZ license.
Catalog note: The address at 1124 S. University Boulevard is identified in the surviving accounts as Reynolds’s home and early operating site; it should not be read as a later commercial studio or transmitter address.
FROM THE TIMELINE
Moments in KLZ-AM History
9ZAF begins experimental broadcasting from the Reynolds home
Dr. William D. “Doc” Reynolds operated amateur station 9ZAF from his home at 1124 S. University Boulevard in Denver. Reynolds used the station for experimental radiotelephone broadcasts and music, laying the groundwork for KLZ.
KLZ receives Colorado’s first broadcasting license
On March 10, 1922, the Department of Commerce issued Reynolds Radio Company a broadcasting authorization with the call letters KLZ. It was the first broadcasting license issued in Colorado under the new federal broadcasting rules.
KLZ moves to 560 AM under General Order 40
As part of the Federal Radio Commission’s nationwide frequency reallocation, KLZ was assigned to 560 kHz on November 11, 1928. The station has remained on 560 AM since.
Time-Life acquires KLZ Radio and Television
Time-Life acquired KLZ Radio and KLZ-TV in 1954, placing the historic Denver radio operation and its young television sister under the media company’s ownership.
KLZ-FM pioneers Denver freeform album rock
In the late 1960s, KLZ-FM became one of Denver's early FM outlets for stereo freeform album rock. The station helped establish progressive FM rock in the market before its call letters later changed to KAZY.
KAZY emerges from KLZ-FM on 106.7
During the 1970s, Denver's pioneering KLZ-FM rock service became KAZY 106.7. KAZY developed into one of Denver's major album-rock stations and later competed directly with KBPI and KBCO.
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