KMBZ, formerly KMBC, traces its ancestry to amateur station 9AXJ, started by Arthur B. Church in 1921. On May 12, 1932, a Federal Radio Commission hearing examiner recommended approval of an application to move the then KMBC transmitter facility from Independence, Missouri, to a site in the northeastern corner of Johnson County, Kansas. KMBC moved to the site at the corner of 50th and Belinder Road in the fall of 1933, and officially inaugurated programming from the site on November 25, 1933.
High winds have toppled broadcast towers twice at the 50th Street and Belinder Road site. At 5:40 pm on June 6, 1938, a 55-mile-per-hour gust of wind took down a single 256-foot tower. Then on August 25, 1941, a 73-mile-per-hour wind caused both towers in KMBC's directional array to crumple to the ground. The taller 544-foot tower, erected the year before, crashed into a nearby house on Booth Street with three people inside. No one was injured.
The City of Westwood was incorporated in 1949.
KMBC-AM/TV was sold to Metromedia Broadcasting Co. on August 29, 1961. Metromedia separated KMBC-AM/FM from KMBC-TV by the sale of the radio stations to Bonneville Broadcasting on May 12, 1967. Bonneville chose the call letters KMBZ for the AM station and KMBR for the FM station. Under FCC rules at the time, either the radio stations or the TV station would have to change call letters because of the ownership split.
On January 6, 1997, Bonneville Broadcasting announced plans to trade KMBZ and its other Kansas City stations, along with its Seattle stations, to Entercom (Entertainment Communications) of Philadelphia in exchange for KLDE(FM) Houston and $5 million cash. Entercom assumed control of the Kansas City Bonneville stations on March 1, 1997.
A Special Use Permit - which is a form of a zoning approval process - has been considered and approved on the Entercom property for the two broadcast towers since at least 1994 when the last building addition was proposed and constructed. The underlying zoning of the subject eight-acre property at the northeast corner of 50th and Belinder Ave is the R-1, Single-Family zoning district. \
An application to rezone the property to a planned commercial office zoning district was submitted in June of 2001 to allow the radio station to expand the building and parking lot. The rezoning was to also allow Entercom to operate the offices and studios on the property “by-right” vs. the Special Use Permit approval process, which is subject to renewal every two to five years.
The rezoning request was approved by the Westwood City Council in September of 2002 (Ord. 836) based on specific submitted building and parking lot expansion plans. Several stipulations of approval were noted with the rezoning approval, including completion of the expansion project within three years; limiting the total number of employees allowed on site to 180 individuals; limiting the total occupancy to 300 for special events; limiting the size of building to a total of 41,000 sq. ft.; and the granting a leasehold interest on the property for 20 years to the City of Westwood for a dedicated green space area.
In August of 2004, Entercom Communications Corp. announces the move of its offices and studios to a location near SM Pkwy and Metcalf Ave in Mission, Kansas away from the site in Westwood.
A Green Space lease agreement was proposed in 2005 by Westwood leadership to utilize a portion of the Entercom property for active open space, and to replace the existing perimeter chain-link fence with a new decorative wrought-iron/stone column fence with lockable gates. This Green Space lease agreement was never executed.
The time limit for completion of the Entercom building expansion project as a term of approval of Ordinance 836 was not met, and the rezoning of the property to the office zoning district was invalidated. The Special Use Permit for the two communication towers remain in place.
During the review and consideration for the renewal of a Special Use Permit for this subject property in 2008, the engineering structural integrity of the two broadcast towers was thoroughly examined. Structural engineering reports were subsequently submitted, and ultimately several upgrades were made to both tower structures to bring them into current engineering standards under TIA/EIA-22-F.
An area teenager trespassing on the property was killed after falling from one of the towers at the site on May 17, 2008.
As of 2015, the facility broadcasts two AM radio stations frequencies from the site – KMBZ at 980 kHz and KUDL at 1660 kHz.
Following the approval of the renewal of a Special Use Permit in April of 2014, the eight-foot tall chain link fence topped with barbed-wire that surrounded the Entercom property in Westwood — a point of discontent for some neighborhood homeowners for years — was taken down in May of 2014. The city reminds the residents that the facility is private property, and the open space areas beneath the broadcast tower are not available for recreational purposes.
The Westwood Board of Zoning Appeals in July of 2014 approved a variance for the Entercom land at 50th and Belinder to allow permanent “No Trespassing” signs to be placed in several locations around the nearly eight-acre sized property.
The Shawnee Mission Board of Education on March 28, 2016 approved the district’s purchase of 6.5 acres of the Entercom property at 50th and Belinder. By 2018, the two radio broadcast towers were disassembled and removed from the property.