About WBBM CBS2WBBM-TV traces its history to 1940 when Balaban and Katz, a subsidiary of Paramount Pictures, signed on experimental station W9XBK, the first all-electronic television facility in Chicago. Balaban and Katz was already well known for owning several movie theaters in the Chicago area. In order to establish the station, the company hired television pioneer William C. "Bill" Eddy away from RCA's experimental station W2XBS in New York City. When World War II began, Eddy used the W9XBK facilities as a prototype school for training Navy electronics technicians. While operating the Navy school, Eddy continued to lead W9XBK and wrote a book that defined commercial television for many years.
On September 6, 1946, the station received a commercial license as WBKB (for Balaban and Katz Broadcasting) on VHF channel 4, becoming the first commercial station located outside the Eastern Time Zone; it was also the sixth commercial TV station in the United States behind WNBT (now WNBC), WCBW (now WCBS-TV), WABD (now WNYW) all in New York City; WRGB in Schenectady, New York; and WPTZ (now KYW-TV) in Philadelphia. WBKB aired some of the earliest CBS programs, including the 1947 debut of Junior Jamboree (later renamed Kukla, Fran and Ollie after it moved to NBC in 1948). Channel 4 originally operated as an independent station, since at the time it was not clear that it would be an affiliate of the CBS television network; eventually, WTMJ-TV in Milwaukee became the first television station west of the Eastern Time Zone to affiliate with a major network. One of the station's early highlights was its telecast of the National Football League's championship game between the Chicago Cardinals and the Philadelphia Eagles on December 28, 1947.
In April 1948, WBKB began sharing the market's CBS affiliation with WGN-TV (channel 9), after that station signed on. In 1949, Balaban and Katz became part of United Paramount Theatres, after Paramount Pictures was forced to divest its chain of movie theaters by order of the United States Supreme Court.
WBKB played an indirect role in the demise of the DuMont Television Network. At the time, Paramount Pictures owned a stake in DuMont, however the Federal Communications Commission (FCC) considered DuMont to be a firm that was controlled by the studio. Paramount also owned KTLA in Los Angeles; however as DuMont already owned WABD (now WNYW) in New York City, WTTG in Washington, D.C. and WDTV (now sister station KDKA-TV) in Pittsburgh, the FCC's decision meant neither Paramount nor DuMont could acquire any more television stations. Paramount even launched a short-lived programming service, the Paramount Television Network (no relation to today's cable-only Paramount Network), in 1949, with KTLA and WBKB as its flagship stations; however, the service never gelled into a true television network.