Back in the 1950s XERF 1570 Khz. in Acuna Mexico across the border from Del
Rio, Texas ran 250,000 watts which reached the Canadian area of north Amer
ica. They connected 5-50,000 watt transmitters together to make power. La
ter the Mexican government confiscated the station and today it runs some 1
00KW. They sold a lot of snake oil and religious programs in the day. Day
time they beamed the signal back into Mexico. I have this book entitled "Bo
rder Radio" that documents those Mexican stations from the 1930s forward.
Interesting time for broadcasting.