The highway was first conceived as part of planning studies in the 1940s, and detailed planning for the new freeway began in 1967. Construction was expected to begin after completion of the Spadina Expressway. Early plans had the road travelling beside the
CN route in the southern parts of the then Borough of Scarborough, but later plans were to have the highway continue as an eastern extension of the Gardiner Expressway along the shores of Lake Ontario running along the base of the Scarborough Bluffs, connecting with Highway 401 by incorporating the existing
Ontario Highway 2A, a short stub freeway segment that was part of the original 401 alignment.
The original 1967 proposal would have seen 1,200 homes demolished for the expressway. After fierce opposition to this plan, the City of Toronto redesigned the route in 1973. It was moved entirely to within the
Lakeshore East CN/GO railway corridor, commencing from the Don Valley Parkway/Gardiner Expressway interchange and would be depressed in a deep ditch. The number of homes to be demolished was reduced to 706. However, this did not pacify east Toronto residents who continued to fight the plan. The City shelved the expressway in 1974.