KNBR (AM)

KNBR (680 kHz, "KNBR 680 and 104.5 The Sports Leader") is an AM radio station in San Francisco, California, broadcasting on a clear channel from transmitting facilities in Redwood City, California. KNBR's non-directional 50,000-watt class-A signal can be heard throughout much of the western United States and as far west as the Hawaiian Islands at night. For several decades, KNBR enjoyed a long history as the flagship station of NBC's West Coast radio operations.

Two other stations also use the KNBR brand. KNBR-FM (104.5 FM) in San Francisco has been a full-time simulcast of KNBR's programming since September 6, 2019. KTCT (1050 kHz) is licensed to San Mateo, California, with a transmitter located near Hayward, California. It carried a separate sports format known as The Ticket but was rebranded as a second KNBR in 2003. The Sports Leader is the on-air branding used by all three stations. KNBR maintains its studios at 2001 Junipero Serra Blvd. in Daly City, California.

Between the three stations, games of the San Francisco Giants, San Francisco 49ers, Bay Area Panthers and Stanford Cardinal are broadcast to the San Francisco Bay Area. KTCT was available in the HD format on 1050 kHz but has been broadcasting in analog. In addition, KNBR was simulcast on the HD2 subchannel of KSAN in nearby San Mateo.

KNBR began broadcasting on April 17, 1922, as KPO, a 100-watt station owned by the Hale Brothers Department Store. In 1925, the San Francisco Chronicle newspaper bought half-interest in the operation. It originally was located in the department store at 901 Market between 5th and 6th. It had a horizontal wire antenna on the roof that was so efficient, the station had listeners all over the Pacific Coast.

In 1927, KPO became an affiliate of NBC. A year earlier, NBC started the NBC Orange Network, its third network, serving the West Coast. In 1927, NBC began broadcasting from space rented in the Saint Francis Hotel. It operated there for a short time before moving to the Hunter–Dulin Building's 22nd floor.

In 1933, KPO was sold to NBC's parent company, the Radio Corporation of America. (RCA), Its operation was consolidated into that of its co-owned KGO at the Hunter-Dulin Building. That same year, KPO increased its transmitter power to 50,000 watts following transmitter reconstruction by General Electric. From there, NBC operated its West Coast Orange Network, feeding dozens of stations and operating a news bureau to serve NBC. As NBC's flagship station on the West Coast, KPO had a full-time orchestra, five studios, and produced many live shows. During the rise of Hollywood, NBC's West Coast operation was moved to NBC Radio City Hollywood.

In 1941, just before World War II, NBC constructed NBC Radio City San Francisco at 420 Taylor Street. It was considered one of the best radio facilities built during the "Golden Age of Radio". However, with the network control having been moved to Los Angeles, the San Francisco NBC building was never fully used. (Later, the building housed KBHK-TV and has since been the headquarters of Reddit and Nextdoor.)

During World War II, KPO's news bureau was the major source of NBC news about the war in the Pacific, and operated shortwave radio stations (transmitters located in Dixon) serving the world. It was at the KPO (RCA) shortwave facility that the message was received that Japanese emperor Hirohito had surrendered, ending World War II.