Owned by Cumulus Media, the studios and offices are located at the Radio City building on Shaw Avenue in North Fresno.

Several nationally syndicated programs are carried at night, including Mark Levin, Armstrong & Getty, Red Eye Radio and America in The Morning from Westwood One, a subsidiary of Cumulus Media, the parent company of KMJ-AM-FM.

[3] On March 23, 1922, the San Joaquin Light and Power Corporation was issued a license with the randomly assigned call letters KMJ, for a new Fresno station operating on the 360 meter "entertainment" wavelength.

[4] By coincidence, KMJ had previously been the call sign assigned to a US merchant marine ship, the SS Matoa, in World War I.

[7] The lack of available broadcasting frequencies meant that many localities had to allocate time slots between multiple timesharing stations.

[11] On November 11, 1928, as part of the implementation of a major nationwide reallocation under the provisions of the Federal Radio Commission's General Order 40, KMJ was reassigned to a "local" frequency, 1200 kHz.

McClatchy was intent on improving KMJ's coverage, and competed with KTAB in Oakland (now KSFO in San Francisco) for reassignment to 580 kHz, a "regional" frequency, which was being made available by the Federal Radio Commission.

Eventually, KMJ was awarded the new channel, and the station moved to 580 kHz, effective July 22, 1932, with a power increase from 100 to 500 watts, with unlimited time.

The studios were subsequently used by Valley Public Radio, and later, McClatchy donated the entire building to the Fresno Metropolitan Museum.

In November 2006, KMJ and its sister stations KFPT, KWYE, KSKS, KFJK, KOQO and KMGV were sold by CBS Radio to Peak Broadcasting for $90 million.

As of January 1, 2013, all Premiere syndicated shows, including Rush Limbaugh and Sean Hannity, were moved to Clear Channel-controlled stations in the greater Fresno area.

[21] In 1936, the station constructed a 5,000 watt non-directional transmitter site which used a ⁠ 5 /8⁠ wave antenna located 5 miles east of Fresno at the northeast corner of the Kings Canyon Road and Fowler Avenue intersection.

The remaining 330 feet were stored on the site, with the intention of creating a directional array, although World War II interrupted the project and it never resumed.

[23] KMJ uses a 50,000 watt transmitter into a directional antenna consisting of 4 mast radiators situated at   36°39′37.2″ N, 119°20′52.8″ W ;   36°39′29.2″ N, 119°20′52.8″ W ;    36°39′27.9″  N, 119°20′48.3″  W  ;   and   36°39′36.5″ N, 119°20′47.1″ W ;   each of the towers is 840 feet (256.1 meters) tall.

Due to its location near the bottom of the AM dial, KMJ's daytime signal decently covers much of the Central Valley, as far north as Sacramento and as far south as Bakersfield.