Established in 1944, it was originally a short gravel highway connecting Waubaushene to Port Severn.

North of Port Severn, the route travelled through wilderness within the District of Muskoka for 38 kilometres (24 mi).

[8] When Ontario signed the Trans-Canada Highway Agreement on April 25, 1950, it had already chosen a Central Ontario routing via Waubaushene and Parry Sound;[9] Highway 17 through the Ottawa Valley was announced as a provincially-funded secondary route of the TCH the following day.

[14] The old portions of the route through Waubaushene and Port Severn were transferred to Tay Township on January 29, 1959.

[15] In order to provide better route continuity for motorists travelling from Toronto to Sudbury, several highways were renumbered in the Muskoka area on May 15, 1976.

[3] The entirety of the former route (with the exception of the east-west section of Lake Joseph Road/Muskoka Road 169 west of Foot's Bay) has now been superseded by Highway 400.