History of Secondary Highway 542:
Secondary Highway 542 is a local highway that connects a handful of small communities on Manitoulin Island to Highway 6. Secondary Highway 542 was first depicted on Preliminary Route Plans dated May 1956, and was designated by an Order-in-Council dated May 9, 1956. The new highway was originally 45 miles (72 km) in length. The route began at the Highway 540 Junction near Gore Bay and continued southeasterly across Manitoulin Island to connect with Highway 68 (today's Highway 6) north of South Baymouth. The highway was gravel-surfaced right up until the 1980s, when the highway was paved gradually from Highway 6 westerly towards Gore Bay.
Apart from some minor revisions to the route of Highway 542 in a few locations, the highway has not changed significantly since 1956. A short spur route off of Highway 542 leading to Tehkummah was apparently signed as Highway 542 initially, but was later renumbered as Highway 542A. The route of Highway 542 is signed concurrently with Highway 551 for approximately 10 km west of Mindemoya. Unless posted otherwise, the speed limit on Highway 542 is 80 km/h (50 mph). Services are only available in Mindemoya, and off of the highway in Gore Bay and Tehkummah.