I ran 14 watts of carrier, was 400 miles from the Atlantic and was occasionally heard in Europe. As Fearless Fred once said, "That RF has to go somewhere." It's all about antenna, time of day, and propagation. Mostly I was heard regionally.
Why there was a Dx'er in Italy named Giovanni who used to hear me all the time, even when I wasn't broadcasting. I worried about him.
Straight up, I did know a guy who experimented w/a 1 watt AM transmitter and was heard up and down the East Coast. I never got word if Giovanni heard those tx's?