A handful of superpower FM stations exist in Canada. Superpower
is not quite as common there for several reasons, including that Class
C stations (with a maximum of 100KW power) are authorized throughout
the country. I can't explain why a majority of Canadian superpower
FMs are in Winnipeg.
ON London CFPL-FM 95.9 380,000 100,000 270 C1 MB Winnipeg CITI-FM 92.1 350,000 100,000 239 C MB Winnipeg CJKR-FM 97.5 310,000 100,000 70 C QU Verdun CKOI-FM 96.9 307,000 100,000 217 C1 MB Winnipeg CBW-FM 98.3 160,000 100,000 223 C
What about superpower TV?
There aren't many. In fact, I can only find one in the United States.
The zone boundaries are roughly similar for TV and FM, except that there is no lower-tower zone ("Zone I-A") in California. The power limits are the same in all zones: 100,000 watts for channels 2-6; 316,000 watts for channels 7-13; (325,000 in Canada) 5,000,000 watts on UHF channels 14-83. The tower height limits do change: 300m (1000') for VHF stations in the lower zone, 600m (2000') for the higher zone. UHF stations may go up to 600m everywhere. (however, the distance separations between stations on the same channel do vary)
WIVB-TV  Buffalo, NY is licensed for 100,000 watts at 366m above average terrain. The theoretical power limit for channel 4 at that height should be 67,186 watts, so WIVB is 1.7dB above the limit.
There are seven superpower TVs in Canada:
AB Edmonton CFRN-TV 3 609,000 100,000 217 AB Edmonton CBXT 5 318,000 100,000 204 AB Lloydminster CKSA-TV 2 116,000 100,000 221 AB Lloydminster CITL-TV 4 130,000 100,000 221 NF St. John's CJON-TV 6 212,800 100,000 250 NS Sydney CJCB-TV 4 180,000 100,000 98 QU Rouyn-Noranda CFEM-TV 13 346,000 325,000 233
CFRN-TV's power is 7.8dB above what should be allowed on channel 3. In Lloydminster, not only are CKSA-TV and CITL-TV on the same tower - but they're commonly-owned! Such a "dual-stick" operation is legal in Canada, primarily in lightly populated areas where a second choice in over-the-air TV would be unlikely to exist if it had to compete with the existing station.