"Radio Telephone Broadcasting is now being carried on at eight different points throughout the country . . . . Broadcasting stations, operated either by amateurs or by radio telephone apparatus manufacturers, are now located at Springfield, Mass.; Newark, N.J.; Pittsburgh, Pa.; Detroit, Mich.; Chicago, Ill.; Los Angeles, Cal.; San Francisco, Cal.; and Seattle, Wash; . . . "
By December, 1921 there were actually more than eight locations with organized radio broadcasting in the United States -- the listed localities are likely the more prominent ones which the authors knew about, listed east to west. Moreover, in some of the cities more than one station was making organized broadcasts.
Four of these sites were locations of Westinghouse Electric & Manufacturing Company stations: Springfield [WBZ]; Newark [WJZ]; Pittsburgh [KDKA], and Chicago [KYW]. Detroit was the home of WBL (which three months later would change its callsign to WWJ), operated by the Detroit News. According to Commercial Broadcasting Pioneer, AT&T had been monitoring broadcasting activities by the Detroit News beginning with its amateur station, 8MK, in the fall of 1920. San Francisco at this time had the most broadcasting activity of any U.S. city, beginning in mid-1920, and included a number of experimental stations in the process of being converted to broadcasting service authorizations, plus AGI, operated by the Army at the Presidio.
There is not enough information in Commercial Broadcasting Pioneer to identify the station or stations in Los Angeles and Seattle. No doubt word had filtered back to New York about operations, most likely by local radio firms or newspapers, as was happening in numerous other cities, not mentioned in this memo.