I was surprised to see that some of these stations were transmitting as much as 3500 Watts! The other curiosity that I had was regarding what frequencies would have been used. Some further reading revealed that the answer is, almost any frequency above 1500 kHz. After the sinking of the Titanic, the Radio Act of 1912 forced all US private stations to these frequencies. The familiar 80/75 meter, 40 meter, 20 meter, and 10 meter bands were not standardized until 1927-1928.