History of King's Highway 5A:
King's Highway 5A was established in 1937 by the City of Toronto and its suburbs to divert through traffic on Highway 11 and Highway 5 away from Downtown. Before Highway 5A was established, through traffic on Highway 5 had little choice but to pass through Toronto to access Highway 11 North, because there were few marked through routes which bypassed the city. Highway 5A began at Highway 5 (Bloor Street) near the intersection of Kipling Avenue and headed east along Dundas Street to Scarlett Road. The highway followed Scarlett Road north for a short distance and then followed St. Clair Avenue easterly to Highway 11 (Yonge Street). It appears that the entire portion of the route through Toronto was considered to be a connecting link by the Department of Highways, as the highway does not appear in any of the Department's highway mileage logs. The highway's total length was reported by the Ontario Motor League as being 35.4 km.
A section of Highway 5A also existed in Scarborough Township. The Scarborough section of Highway 5A ran along Eglinton Avenue from Dawes Road (today's Victoria Park Avenue) to Highway 2 (Kingston Road). This section of Eglinton Avenue was assumed by the Department of Highways in 1937. However, based on the mileage of the road allowances assumed west of Dawes Road, it appears that the Department of Highways originally intended to extend Highway 5A across the Don River to Leaside. At that time, Eglinton Avenue ended at the Scarborough Township boundary at Dawes Road and resumed again in Leaside. However, the gap in Eglinton Avenue was never completed as a provincial highway, so the east and west segments of Highway 5A were never directly connected. In 1953, the eastern leg of Highway 5A from Dawes Road to Highway 2 (Kingston Road) was re-designated as Highway 109. The western leg of Highway 5A was decommissioned as a marked King's Highway in 1952.