KZAC's studios are located on Battery Street in San Francisco, while the transmitter resides near the Islais Creek Channel.

Capital Cities/ABC Inc. bought KSFO in 1995 and shifted its programming to emphasize conservative talk, and was one of the most popular stations in San Francisco through the late 1990s.

A 2024 programming realignment by current owner Cumulus Media saw KSFO's format and branding moved to 810 AM and this facility renamed as KZAC.

On August 1, 1925, the bureau sent a telegram[2] authorizing a new radio station for the Tenth Avenue Baptist Church in Oakland, California, operating on 1390 kHz.

[4] National programs on KSFO included Alka-Seltzer Newspaper of the Air, Cowboy Church with Stuart Hamblen, and Father Coughlin.

[4] Nearly seven months after the Federal Communications Commission (FCC) granted a construction permit, KSFO began broadcasting at its current power of 5,000 watts from a new 389-foot steel transmitter at Pier 92 and Islais Creek.

Effective December 31, 1941, KSFO was no longer affiliated with CBS Radio, after the network moved to KQW in San Jose.

[citation needed] KSFO again moved its studios in August 1943, this time to the Mark Hopkins Hotel, with which The Associated Broadcasters signed a long-term lease in 1942.

As a result, KSFO joined three other Bay Area radio stations, KLX, KROW, and KYA, in a collective bargaining agreement.

From its first season moving from New York in 1958 to 1978, the San Francisco Giants broadcast their games on KSFO, with notable announcers including Russ Hodges, Lon Simmons, Al Michaels, and Joe Angel.

KSFO continued playing Frank Sinatra, Tony Bennett, and Peggy Lee, whose music had been phased out of many MOR stations.

Starting in 1981, KSFO was the radio home of the Oakland A's, with a broadcast team of Bill King, Lon Simmons, and Wayne Hagin.

[35] In June 1983, Golden West reached an agreement to sell KSFO to Seattle-based King Broadcasting Company, which also owned KYA and KLHT (later KYA-FM) in San Francisco, for a reported $8 million.

[36] King Broadcasting brought back former KSFO personality Al "Jazzbo" Collins from WNEW in New York City to host a late night jazz show.

[38] In July 1986, seeking to attract Baby Boomer listeners, King Broadcasting changed KSFO's music format to be similar to KYA-FM.

[48] The FCC ruled that the transfer was "consistent with the public interest and would have no effect on diversity and competition in the San Francisco market.

[47] With the brand "Hot Talk 560" and slogan "The Station for Right-Thinking People," the station introduced a lineup that had J. Paul Emerson hosting morning drive, The Savage Nation with Michael Savage in afternoon drive, and syndicated shows hosted by Ken Hamblin, Michael Reagan, and Pat Buchanan.

[47] In addition, the new KSFO carried news updates from ABC Direction, and Stanford football broadcasts returned for the first time since 1984.

[65] After the 1997 season, KSFO stopped broadcasting Stanford football, which moved to upstart sports station KTCT, formerly KOFY-AM.

[71] In a time period with the Clinton–Lewinsky scandal and a California gubernatorial election dominating the news, KSFO was a top-10 station in San Francisco's Arbitron ratings throughout 1998.

... KSFO Radio has been described in tones of hysteria as a cauldron of racism and homophobia, a wacko gun-nut unit, a nest of conspiracy theorists spouting political paranoia.

[85] In the same month, Disney announced a $2.7 billion sale of ABC Radio Networks and 22 stations, including KSFO and KGO, to Citadel Broadcasting.

[88] Morgan attracted media attention in June 2006 after suggesting anyone convicted of treason be sent to the gas chamber, including New York Times editor Bill Keller.

[90] Spocko began a letter-writing campaign to advertisers on KSFO, alerting them to these examples and urging them to withdraw their support of the station.

[92][93] On December 22, 2006, ABC lawyers sent a cease and desist letter to Spocko, demanding that he remove the KSFO audio clips due to copyright violations.

[94] On January 12, 2007, KSFO preempted the Laura Schlessinger show for a special three-hour program where Morgan, Rodgers, and Sussman responded to Spocko and other critics.

Due to budget constraints that resulted from parent company Citadel Broadcasting losing over $800 million in the fourth quarter of 2007, KSFO declined to renew Morgan's contract after it expired on March 31, 2008.

[98] Meanwhile, declining advertising revenue and $2.5 billion in debt led Citadel Broadcasting to file for Chapter 11 bankruptcy in December 2009.

This move followed programming changes throughout local radio at the end of 2011, starting with sister station KGO laying off many of its talk show hosts.

[111] Beginning September 29, 2014, the Limbaugh and Hannity shows returned to KSFO after their former Bay Area station, KNEW (960 AM), changed to Bloomberg Radio.