The Canso Causeway was built at a narrow location on the Strait of Canso, about 6 kilometers northwest of Port Hawkesbury and Mulgrave, http://ca.distancescalc.com/calculate?from=canso+causeway&to=port+hawkesbury crossing from Cape Porcupine near Auld's Cove on the Nova Scotia side to Port Hastings on the Cape Breton side.