If Trudeau had not shoved metric down our throats the Ontario Conservative lunatics of the day would have never got the limit lowered to 80kph from 102 kph (60 mph).
I believe the limited change before metric came in , I REMEMBER SEEING SIGNS AT 70 mph and then dropping to 60 mph along the 400
What was the speed limit on Ontario's early highways?
A. Ontario's first province-wide speed limit on rural highways was introduced in 1903 at 15 mph (24 km/h). The speed limit was increased to 25 mph (40 km/h) by the early 1920s and increased further to 35 mph (56 km/h) by the late 1920s. In 1937, the opening of the new Middle Road superhighway between Toronto and Hamilton prompted another review of the speed limits on Ontario highways. The speed limit on most rural highways was increased to 50 mph (80 km/h) in May 1937. During World War II, the speed limits were temporarily lowered to 40 mph (65 km/h) to conserve Canada's fuel supplies. The next speed limit increase took place in 1959, when the speed limit for passenger cars using the new superhighways such as Highway 400 and Highway 401 was changed to 60 mph (100 km/h). The speed limit for trucks and heavy vehicles on the superhighways was increased to 55 mph (90 km/h) in 1959. On some high standard two-lane highways, the speed limit for passenger cars was increased as high as 60 mph (100 km/h) in 1959. In the late 1960s, the speed limit on the 400-Series Highways was increased again to 70 mph (115 km/h) for passenger cars and 60 mph (100 km/h) for trucks and heavy vehicles. During the energy crisis of the mid-1970s, the speed limit for passenger vehicles was changed back to 60 mph (100 km/h). The energy crisis also brought about the reduction of speed limits on most conventional highways back to a maximum of 55 mph (90 km/h). During the conversion to Metric measurements in 1977, the speed limit on most conventional highways was reduced even further to 80 km/h. Since the 1970s, the speed limit on Ontario freeways has generally remained at 100 km/h (60 mph), while conventional highways have generally remained at 80 km/h (50 mph).