K-146 was designated between 1957 and 1960 and first appeared on the 1960-61 edition of the state highway map.

Highway 27 was first designated between Barrie and Penetanguishine on September 14 1927.

When the state highway system was first signed in 1919, M-41 was designated between Holton and Hart.

This route was designated between 1995 and 1998 in stages as a limited access bypass route was constructed to the north of these towns.

As a result, few critical habitats were designated between 1986 and the late 1990s.

The route was designated between 1933 and 1936.

SH 220 was designated between 1936 and 1939 along its current route.

The route was designated between 1936 and 1938 along its current route.

A new M-85 was then designated between Mayville and Caro.

The highway was designated between Jasper and Parthenon in 1966, following its current alignment between the communities.