Under the provisions of the FRC's General Order 40, a sweeping reallocation of station frequency assignments was implemented on November 11, 1928.
KYW was assigned to the clear channel frequency of 1020 kHz, but the assignment caused two major problems.
KYW's signal on the new frequency experienced difficulties in covering the entire city of Chicago.
A relay transmitter, KYWA, was set up in late 1928, although it was no longer needed by the spring of 1930.
A second issue was that, under the provisions of the "Davis Amendment", eight clear channel frequencies were to be allocated to each of five national regions.
Chicago was located in Region 4, while the reallocation provisions had reserved 1020 kHz for use in Region 2, a grouping of mid-Atlantic states.

Westinghouse fought a long legal battle, attempting to keep KYW operating as a clear channel station on 1020 in Chicago.
Finally it proposed moving the station to a Region 2 location, settling on Philadelphia.
However, numerous other stations made alternative proposals to be assigned this allocation, and the matter was placed in the hands of an FRC examiner, who held hearings in July 1932 to sort through 23 conflicting applications from 16 stations.
Examiner Pratt's recommendation concluded that KYW's willingness to move to Philadelphia was the best possible outcome.

After broadcasting its last program in Chicago on December 2, 1934, KYW aired its debut Philadelphia program the next day.
Westinghouse used the studios and sales operations of WCAU.
The move made KYW the easternmost U.S. radio station with a call sign beginning with "K".
KYW became Philadelphia's NBC-Blue Network outlet, an affiliation that lasted 20 years.
 The move supplanted WFI and WLIT (which merged as WFIL in 1935), as the Blue Network affiliate.
In 1938 KYW's studios were located at 1619 Walnut Street in Center City.

On March 29, 1941, KYW's clear channel assignment was shifted from 1020 to 1060 kHz, its current frequency, as part of a nationwide adjustment of assignments engineered by the North American Regional Broadcasting Agreement (NARBA).
In 1942, the Federal Communications Commission (FCC) compelled RCA to divest itself of one of its two radio networks.
Prior to the divestiture of the NBC-Blue network (which became the American Broadcasting Company), KYW, along with the other Westinghouse radio stations, became affiliated with the NBC-Red Network, predecessor of modern-day NBC.
Also in 1942, KYW added an FM station at 45.7 megacycles, W57PH.
It largely simulcast KYW's programming and later moved to 92.5 MHz as KYW-FM when the FM dial was shifted.
But development of FM radio was slow and Westinghouse decided to shut down KYW-FM in 1955.

KYW acquired a television counterpart in 1953, when Westinghouse bought Channel 3 WPTZ (now KYW-TV), the nation's third commercial television station and NBC's second television affiliate.
Under the provisions of the FRC's General Order 40, a sweeping reallocation of station frequency assignments was implemented on November 11, 1928. KYW was assigned to the clear channel frequency of 1020 kHz, but the assignment caused two major problems. KYW's signal on the new frequency experienced difficulties in covering the entire city of Chicago. A relay transmitter, KYWA, was set up in late 1928, although it was no longer needed by the spring of 1930. A second issue was that, under the provisions of the "Davis Amendment", eight clear channel frequencies were to be allocated to each of five national regions. Chicago was located in Region 4, while the reallocation provisions had reserved 1020 kHz for use in Region 2, a grouping of mid-Atlantic states.
Westinghouse fought a long legal battle, attempting to keep KYW operating as a clear channel station on 1020 in Chicago. Finally it proposed moving the station to a Region 2 location, settling on Philadelphia. However, numerous other stations made alternative proposals to be assigned this allocation, and the matter was placed in the hands of an FRC examiner, who held hearings in July 1932 to sort through 23 conflicting applications from 16 stations. Examiner Pratt's recommendation concluded that KYW's willingness to move to Philadelphia was the best possible outcome.
After broadcasting its last program in Chicago on December 2, 1934, KYW aired its debut Philadelphia program the next day. Westinghouse used the studios and sales operations of WCAU. The move made KYW the easternmost U.S. radio station with a call sign beginning with "K". KYW became Philadelphia's NBC-Blue Network outlet, an affiliation that lasted 20 years.  The move supplanted WFI and WLIT (which merged as WFIL in 1935), as the Blue Network affiliate. In 1938 KYW's studios were located at 1619 Walnut Street in Center City.
On March 29, 1941, KYW's clear channel assignment was shifted from 1020 to 1060 kHz, its current frequency, as part of a nationwide adjustment of assignments engineered by the North American Regional Broadcasting Agreement (NARBA). In 1942, the Federal Communications Commission (FCC) compelled RCA to divest itself of one of its two radio networks. Prior to the divestiture of the NBC-Blue network (which became the American Broadcasting Company), KYW, along with the other Westinghouse radio stations, became affiliated with the NBC-Red Network, predecessor of modern-day NBC. Also in 1942, KYW added an FM station at 45.7 megacycles, W57PH. It largely simulcast KYW's programming and later moved to 92.5 MHz as KYW-FM when the FM dial was shifted. But development of FM radio was slow and Westinghouse decided to shut down KYW-FM in 1955.
KYW acquired a television counterpart in 1953, when Westinghouse bought Channel 3 WPTZ (now KYW-TV), the nation's third commercial television station and NBC's second television affiliate.
KYW (AM)