History of Secondary Highway 548:
Secondary Highway 548 is a local highway that serves as an access route for a number of small communities on St. Joseph Island in the District of Algoma southeast of Sault Ste. Marie. Highway 548 was designated by an Order-in-Council dated May 9, 1956 and was first depicted on a Preliminary Route Plan dated June, 1956. The new highway was originally 46 miles (74 km) in length. The route began at Highway 17 between Echo Bay and Desbarats and headed southerly to the St. Joseph Island Ferry Dock. From there, a Department of Highways' Ferry crossed the North Channel and connected the non-contiguous north section of Highway 548 on the Mainland to the balance of the route of Highway 548 situated on St. Joseph Island. Highway 548 continued south from the Ferry Dock at Humbug Point at the northern tip of the island towards Hilton Beach. From there, Highway 548 gradually looped its way around the entire island, before the highway ultimately connected up with itself again at Kent's Corners at the north end of the island. The route of Highway 548 was gravel-surfaced for its entire length when it was first designated in 1956. However, a 12-mile section of the highway from the Highway 17 Junction to Hilton Beach was paved in 1959. A section of Highway 548 from Kent's Corners to west of Richards Landing was paved in 1963 and another section of Highway 548 southwest of Richards Landing was paved in 1966. Paving was completed on Highway 548 southerly to the K-Line Road in the Kentvale area in 1973. Another section of Highway 548 south of Hilton Beach was paved in 1971. The balance of Highway 548 around the southern end of St. Joseph Island was not paved until the late 1980s.
In the early 1970s, a new bridge was constructed to permanently link St. Joseph Island to the Mainland. Construction began on the new bridge in 1970, and work was completed three years later. The new St. Joseph Island Bridge on Highway 548 was completed and officially opened to traffic on September 25, 1973. Ferry service to St. Joseph Island ceased in 1973, once the new bridge was completed. Apart from some minor revisions to the route of Highway 548 in a few locations, the highway has not changed significantly since 1956. Unless posted otherwise, the speed limit on Highway 548 is 80 km/h (50 mph). Services are rather scarce on Highway 548. Services are only available at the Highway 17 Junction, Kent's Corners, Richards Landing, Hilton Beach and Kentvale.