 Highway 89 was established in 1937 as a result of the rerouting of Highway 9 between Orangeville and Highway 27 . In 1963 , the route was extended west to Palmerston and east to Highway 400 . Plans were conceived during the late 1970s to push the highway further east to Highway 12 via Ravenshoe Road , resulting in a brief extension to Highway 11 . However , environmental protest over the chosen route through the Holland Marsh resulted in the cancellation of plans in 1986 . In 1997 , the section between Highway 400 and Highway 11 was decommissioned . The most recent change to the route took place in 2003 , when the section of Highway 89 between Palmerston and Harriston was renumbered as part of Highway 23 , creating a shared terminus at a junction with Highway 9 . 
