Wikipedia
KZY was a radio station located in Oakland, California, that was licensed to the Atlantic-Pacific Radio Supplies Company from December 9, 1921 until its deletion on January 24, 1923. It, and the Preston D. Allen station, KZM, were the first broadcasting stations licensed to Oakland.
KZY was the successor to Experimental station 6XC, which dated to mid-1920, and which founder Lee de Forest suggested deserved credit as the "first radio-telephone station devoted solely" to broadcasting to the public. Including its predecessor, KZY's broadcasting history predated that of many better known pioneer stations, including WWJ in Detroit, Michigan (started August, 1920, originally as 8MK) and KDKA in Pittsburgh, Pennsylvania (debuted November 2, 1920 as 8ZZ).