I'm not sure when the Gate of Horn opened, but it was going in the mid-50s. The radio program "The Midnight Special" started in 1953. The Old Town School of Folk Music started in 1957. These were symptoms of the interest in folk music that had been developing slowly over a number of decades, but in the 50s, the wave was beginning to crest. There were folksingers singing in front of audiences in coffeehouses and clubs all over the country in the 50s.

The fact that the Kingston Trio's first album sold well was a RESULT, not the cause, of the folk music revival in the United States.