History of Secondary Highway 556:
Secondary Highway 556 is a minor collector highway in the District of Algoma that provided access to a number of small communities lying northeast of Sault Ste. Marie. Highway 556 was first designated by an Order-in-Council dated May 9, 1956. The route was first depicted on a Preliminary Route Plan prepared by the Department of Highways of Ontario (DHO) in June, 1956. The new highway was originally 22 miles (35 km) in length. Initially, Highway 556 began at the Highway 17 Junction at Island Lake, north of Heyden and headed northeasterly where it ended at the Christina Mine Road near Wabos. The highway was gravel-surfaced at the time of designation in 1956, but was paved from the Highway 17 Junction to Searchmont in 1964. The massive Heyden-Goulais River Diversion was completed on Highway 17 in 1960, which bypassed about 18 km of the existing route of Highway 17. The bypassed section of Highway 17 from Heyden to the Highway 556 Junction at Island Lake was re-designated as a Secondary Highway by an Order-in-Council, effective August 3, 1961. Old Highway 17 from Heyden to Island Lake was subsequently renumbered as an extension of Highway 556, while the bypassed sections of Highway 17 lying between the Highway 556 Junction at Island Lake and the realigned Highway 17 north of Goulais River were renumbered as Highway 552 & Highway 552A.
A significant extension was made to the route of Highway 556 during the 1970s. In February 1976, a Preliminary Assumption Plan was prepared by the Ministry of Transportation and Communications (MTC) which showed the proposed assumption of a forest access road known as the Ranger Lake Road. This forest access road began in Searchmont and extended northeasterly for approximately 80 km to Highway 129 near Aubrey Falls. The plan was registered on April 1, 1976 and the extension was formally designated as Highway 556 by an Order-in-Council, effective May 19, 1976. The bypassed north leg of Highway 556 from Searchmont to Wabos was subsequently renumbered as Highway 532. Apart from some minor revisions to the route of Highway 556 in a few locations, the highway has not changed significantly since the 1970s. Highway 556 is still gravel-surfaced from the Highway 532 Junction at Searchmont to the Highway 129 Junction. The balance of Highway 556 is paved. Unless posted otherwise, the speed limit on Highway 556 is 80 km/h (50 mph). Services are only available at the Highway 17 Junction in Heyden and on Highway 532 in Searchmont. There are no services available along Highway 556 east of Searchmont.