The Port of Saint John continued to grow over the years. In 1934, workers completed a massive expansion project that added a 17-acre Navy Island terminal to the port. Later the same year, crews completed a new channel to replace the original Z-Shaped channel, which had been difficult for ships to navigate. During 1948 to 1952, workers reconstructed the Pugsley Terminal berths. Ten years later, work crews completed extensive renovations to the Long Wharf Terminal.

Over the passing years, the Port of Saint John developed various new types of import and export businesses. The port also entered into containerized shipping, and in 1972, completed the Rodney Container Terminal on the west side of the harbour. This new terminal gave the port increased capacity to handle containers. By the mid 1970's, the Port of Saint John was dealing with 13 container-shipping lines.