Actually, the Port of New York was very busy in the 60's, 70', and early 80's. They had both Home Lines and HAL sending 2 ships a piece to both the Bahamas and Bermuda every week from April to Oct. During winter months they did 10 to 14 night Caribbean cruises. In addition, You had Sea Venture (later the first Princess ships) Incres Lines, Italian Line, Swedish America and Norwegian America doing a combination of Caribbean and TransAtlantics. This is in additional to the traditional Cunard departures. I'm sure I forget to name a few of the others.
Mark