When the North American Regional Broadcast Agreement (NARBA) set up the highest designation for an AM radio station, I-A, only 38 stations were chosen. Only a few cities got more than one.
Chicago got four (670 WMAQ, 720 WGN, 780 WBBM, 890 WLS)
New York got three (660 WEAF-WNBC, 770 WJZ-WABC, 880 WCBS)
Mexico City got three (730 XEX, 900 XEW, 1220 XEB)
Toronto got two (740 CBL, 860 CJBC)
Los Angeles and Montreal came close to having two I-As. LA got 640 KFI as a I-A. Meanwhile 1070 KNX was equal to a Class I-A. It was 50,000 watts non-directional. But it was a I-B because it shared its frequency with CBA Moncton. New Brunswick was so far from California that CBA also was 50,000 watts non-directional. But you could only have one I-A on one frequency. So that knocked KNX and CBA down to I-B status.
Montreal had a similar story. 690 CBF was a I-A. CBM 940 came close. It only had a slight directional adjustment to its nighttime signal. But it was protecting XEQ 940 in Mexico City. They were far from each other and XEQ was non-directional at all times. But being on the same frequency, they were both I-Bs.
You'd think some other big cities would get more than a single I-A but that didn't happen.
Dallas-Fort Worth got a I-A (820 WBAP) and a I-B (1090 KRLD)
Nashville got a I-A (WSM 650) and I-B (WLAC 1510)
Philadelphia got a I-A (WCAU 1210) and a I-B ( KYW 1060)
Monterrey got a I-A (XEG 990) and a I-B (XEMR 1140)
Minneapolis-St. Paul got a I-A (WCCO 830) and a I-B (KSTP 1500)
Chicago got four (670 WMAQ, 720 WGN, 780 WBBM, 890 WLS)
New York got three (660 WEAF-WNBC, 770 WJZ-WABC, 880 WCBS)
Mexico City got three (730 XEX, 900 XEW, 1220 XEB)
Toronto got two (740 CBL, 860 CJBC)
Los Angeles and Montreal came close to having two I-As. LA got 640 KFI as a I-A. Meanwhile 1070 KNX was equal to a Class I-A. It was 50,000 watts non-directional. But it was a I-B because it shared its frequency with CBA Moncton. New Brunswick was so far from California that CBA also was 50,000 watts non-directional. But you could only have one I-A on one frequency. So that knocked KNX and CBA down to I-B status.
Montreal had a similar story. 690 CBF was a I-A. CBM 940 came close. It only had a slight directional adjustment to its nighttime signal. But it was protecting XEQ 940 in Mexico City. They were far from each other and XEQ was non-directional at all times. But being on the same frequency, they were both I-Bs.
You'd think some other big cities would get more than a single I-A but that didn't happen.
Dallas-Fort Worth got a I-A (820 WBAP) and a I-B (1090 KRLD)
Nashville got a I-A (WSM 650) and I-B (WLAC 1510)
Philadelphia got a I-A (WCAU 1210) and a I-B ( KYW 1060)
Monterrey got a I-A (XEG 990) and a I-B (XEMR 1140)
Minneapolis-St. Paul got a I-A (WCCO 830) and a I-B (KSTP 1500)
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