History of Secondary Highway 551:
Secondary Highway 551 is a local highway that connects a handful of small communities in the central portion of Manitoulin Island. Secondary Highway 551 was first depicted on a Preliminary Route Plan dated April 1956, and was designated by an Order-in-Council dated May 9, 1956. The new highway was originally 18 miles (29 km) in length. The route originally began at the Providence Bay Government Dock and continued northeasterly across Manitoulin Island to connect with Highway 540 at M'Chigeeng (West Bay). The highway was gravel-surfaced up until 1977, when the highway was paved between the Highway 540 Junction and Mindemoya. The balance of the highway was paved in the early 1980s.
Apart from some minor revisions to the route of Highway 551 in a few locations, the highway has not changed significantly since 1956. The route of Highway 551 is signed concurrently with Highway 542 for approximately 10 km west of Mindemoya. The southernmost 300 metres of Highway 551 was decommissioned in the 1990s. This short section of Highway 551 from Government Road to Tehkummah and the Provindence Bay Government Dock was transferred to the Township of Carnarvon on May 11, 1994. Unless posted otherwise, the speed limit on Highway 551 is 80 km/h (50 mph). Services are only available in Mindemoya and M'Chigeeng (West Bay).