It was then that a causeway to connect the mainland of Nova Scotia and Cape Breton Island was recommended at a cost of ten million more than a low level bridge which was first suggested. The causeway was proposed to cost $22,760,000 in total including a navigation lock and bridge on the Cape Breton side which would allow ships with a 30 foot draught to pass through the strait.
Once the contracts were awarded, it took only three months to assemble a rock quarry, build access roads, assemble heavy equipment and build camps for workers. Construction officially began on the Canso Causeway in September of 1952. The construction phase is still regarded as one of the biggest engineering feats in the area today. The Canso Causeway officially opened on August 13,1955. The rock used to build the causeway was blasted from a nearby rock quarry at Cape Porcupine. In total, some 10,092,000 tons of rock were used to close the Strait of Canso. Approximately 125,000 tons of rock came crashing to the ground with each blast. The Canso causeway is 860 feet wide at the ocean floor which is eight times the width of its crest. The span of the causeway is one mile long and 80 feet wide. It forms the shape of an"S". The Canso canal measures 1,870 feet in length and is also eighty feet wide. Approximately 98,000 cubic yards of concrete was used to build the canal. The swing bridge at the canal measures 308 feet long. The contsruction phase terminated on Friday December 10, 1954. The causeway officially opened on August 13, 1955.

It provided the strait area with a deep water ice-free port on the Port Hawkesbury and Mulgrave side which allowed large companies to settle in the strait area. The ice free port allowed large vessels to come into the Port Hawkesbury and Mulgrave towns year round. The bulk of industrial activity in Cape Breton Island shifted away from the Sydney area to Port Hawkesbury and nearby Point Tupper, many of which still exist today. The town of Port Hawkesbury grew in population to 5000 citizens mainly due to the industrialization and spinoffs from these large industrial companies moving there since completion of the causeway. The major industrial companies that relocated to the area are Stora Enso, a pulp and paper mill which is the largest employer of the region. Statia Terminals, a gas and oil shipping and refining company moved to the area since they could bring the world's largest vessels to the ice free port year round. Nova Scotia Power built a generating plant to assist the major industrial companies of the area.