Highway 27 was designated as a two-lane road travelling north from Highway 2 (Lake Shore Boulevard) towards Barrie. As Toronto grew outwards following the annexation of various municipalities, the Ontario Department of Highways (DHO) began planning for a bypass of the city, aptly named the "Toronto Bypass". A significant portion of this bypass was designed to be incorporated into the Transprovincial Highway, now Highway 401. The remainder was designed to follow the existing right-of-way of Highway 27 between the QEW and Richview Sideroad (now Eglinton Avenue).