The Westinghouse Electric and Manufacturing Company entered broadcasting with the November 2, 1920, sign-on of KDKA radio in Pittsburgh.

Most of the Blue Network's programming originated at WJZ, which in 1923 had its license moved to New York City, and its ownership transferred to RCA.

In 1931, Westinghouse switched the call letters of its two Massachusetts stations, with WBZA moving to Springfield and WBZ going to Boston.

[11] The North American Regional Broadcasting Agreement of 1941 saw all of Westinghouse's original stations move to their current frequencies.

A decade later, the FCC forbade common ownership of two or more clear channel stations with overlapping nighttime coverage, though the commission allowed Westinghouse to keep WBZ, KYW, KDKA, and WOWO together under a grandfather clause.

Westinghouse expanded to the West Coast in 1944 with its purchase of 5,000-watt KEX in Portland, Oregon,[12] a station which also shared a frequency with WOWO.

Westinghouse built FM sister stations for WBZ/WBZA, KDKA, KYW, KEX, and WOWO, all of which were on the air by the end of the decade.

During the 1970s and 1980s, WIND also tinkered with a part-time news format, though it had little success against the dominant all-news station in Chicago, CBS-owned WBBM.

Using sophisticated mathematical modeling, the group promoted its "New Math Calculator" which became extremely popular in ad agencies for planning radio campaigns.

This was no simple look-up table; it introduced innovative measures such as "reach index" and "gross cume" to operationalize its core models.

Over the next quarter-century, Westinghouse would purchase several other radio stations, including KFBK in Sacramento, California; WNEW-FM in New York, KTWV in Los Angeles, and WMMR in Philadelphia.

[22] WOWO was sold to other interests in 1982[23] and WIND was spun off in 1985,[24] two years before Group W bought WMAQ from NBC after that network announced it was closing its radio division.

[27] KPIX in San Francisco was bought in 1954;[28] WDTV (now KDKA-TV) in Pittsburgh was added in 1955;[29][30] and WAAM (now WJZ-TV) in Baltimore was purchased in 1957.

In exchange Westinghouse received NBC's Cleveland stations, WTAM radio and WNBK television, along with $3 million in compensation.

[40] The deal was approved in January 1956;[41] one month later Westinghouse moved the KYW call letters to Cleveland and NBC renamed the Philadelphia stations WRCV (AM) and WRCV-TV.

However, the ink had barely dried on FCC approval of the trade when the United States Department of Justice opened an investigation into the deal, on claims that NBC had employed extortion and coercion.

Based on these findings, a civil antitrust suit was filed against NBC and its parent company RCA, on behalf of Westinghouse in December 1956.

KYW-TV (in both Cleveland and Philadelphia), WBZ-TV, and WPCQ-TV were NBC affiliates, KPIX and KDKA-TV were aligned with CBS, and WJZ-TV was an ABC station.

Westinghouse found no success in the Charlotte market, as WPCQ-by far the smallest station ever owned by the company-remained an also-ran during its Group W years.

It also had to deal with three longer-established NBC affiliates, on VHF channels from nearby cities, that were also available over-the-air in large parts of the Charlotte market.

Westinghouse was able to escape Charlotte when it sold WPCQ (now WCNC-TV) to Odyssey Television Partners (later to become Renaissance Broadcasting) in 1985.

Aside from WPCQ, Group W almost expanded into the country's top two markets; it emerged as a leading bidder for RKO General's independent stations WOR-TV (currently WWOR-TV) in Secaucus, New Jersey (serving New York City), and came to a deal to buy KHJ-TV (currently KCAL-TV) in Los Angeles.

However, protracted legal issues that had dogged RKO General for years delayed the transfer of KHJ-TV, and Westinghouse ultimately withdrew its offer.

[53] To avoid being consigned to the UHF band in two major markets, CBS heavily courted ABC affiliates WXYZ-TV in Detroit and WEWS-TV in Cleveland.

The terms were as follows: A short time later, Westinghouse announced it was buying CBS outright, a transaction which closed in late 1995.

[59] As a condition of the merger, both CBS and Group W were forced to sell off several radio stations due to the FCC's then-current ownership limits.

The Westinghouse-CBS merger resulted in several longtime rivals on the radio dials of New York City, Los Angeles, Chicago, and Philadelphia becoming sister stations.

From that point forward, however, Westinghouse proceeded to transform itself from its legendary role as a diversified conglomerate with a strong industrial heritage into a media giant.

Excluding WMAQ (shut down in 2000 to allow all-sports WSCR to move to its old dial position) and KFWB (placed in a holding trust as a consequence of CBS's purchase of KCAL-TV; the trust divested the station in 2016), all of the former Group W radio stations were part of CBS Radio until its merger with Entercom (now Audacy, Inc.) on November 17, 2017.

In 1992, the Westinghouse Broadcasting International unit has signed a deal with Mitsubishi to represent the catalog for the Japanese market.