WLS-TV (channel 7) is a television station in Chicago, Illinois, United States, serving as the market's ABC network outlet. Owned and operated by the network's ABC Owned Television Stations division, the station maintains studios on North State Street in the Chicago Loop, and its transmitter is located atop the Willis Tower. History WENR-TV (1948–1953) The station first signed on the air on September 17, 1948, as WENR-TV. It was the third television station to sign on in the Chicago market behind WGN-TV (channel 9), which debuted six months earlier in April, and WBKB (channel 4), which changed from an experimental station to a commercial operation in September 1946. As one of the original ABC-owned stations on channel 7, it was the second station to begin operations after New York City, and before Detroit, San Francisco and Los Angeles. The station's original call letters were taken from co-owned radio station WENR (890 AM), which served as an affiliate of the ABC Radio Network (WENR would eventually merge with WLS, with which it shared a frequency under a time-sharing arrangement until ABC purchased a 50% interest in WLS in 1954). WBKB-TV (1953–1968) In February 1953, ABC merged with United Paramount Theatres (UPT), the former theater division of Paramount Pictures. UPT subsidiary Balaban and Katz owned WBKB (which shared a CBS affiliation with WGN-TV). The newly merged American Broadcasting-Paramount Theatres, as the company was known then, could not keep both stations because of Federal Communications Commission (FCC) regulations then enforced that forbade the common ownership of two television stations licensed to the same market. As a result, WBKB's channel 4 license was sold to CBS, which subsequently changed that station's call letters to WBBM-TV; that outlet would move to VHF channel 2 several months later on July 5, 1953. The old WBKB's on-air and behind-the-scenes staff stayed at the new WBBM-TV, while the WBKB call letters and management moved to channel 7 (from 1965 to 1968, a "-TV" suffix was included in the station's calls, modifying it to WBKB-TV). WLS-TV (1968–present) Sterling "Red" Quinlan served as the station's general manager from the early 1950s to the mid-1960s, and became a giant in early Chicago television. Quinlan was instrumental in starting the careers of Tom Duggan, Frank Reynolds and Bob Newhart. The station courageously aired The Tom Duggan Show in the mid-1950s, which became the most popular show in the Chicago market, far outdrawing