In its present form, Highway 24 begins at Highway 3 in the town of Simcoe. The highway once continued south, but this has since been transferred to local jurisdiction and is now Norfolk County Highway 24. From Simcoe, Highway 24 travels north through Oxford County, bypassing to the east of Scotland as it enters Brant County. From there, it meanders northeast towards Brantford Municipal Airport, intersecting former Highway 53 before encountering an interchange with Highway 403 south of Paris. The route joins concurrently with Highway 403 and travels east into Brantford; Highway 24 resumes its northward orientation at the King George Road interchange, splitting from Highway 403. Between Brantford and Cambridge, Highway 24 is a busy two lane rural highway that has played host to frequent collisions, prompting a Ministry of Transportation of Ontario investigation into possible upgrades to the stretch. The route is generally straight and flat as it progresses north through the agricultural countryside of Brant County, but suddenly drops into the Grand River Valley as it enters the Regional Municipality of Waterloo. It follows the river along its eastern bank towards Cambridge, ending at the southern city limits. Within Wellington, Dufferin, Grey and Simcoe counties, the former route of Highway 24 is now designated as County Road 124, while in Waterloo and Peel Regions the route is designated Regional Road 24. This discontinuity has led to motorist confusion, as the route number changes suddenly at boundaries. Within Wellington County, there is also an unrelated County Road 24. The highway is maintained under a Connecting Link agreement in Simcoe and north of Highway 403 in Brantford.
History
Highway 24 was first designated on July 2, 1927, when the Department of Highways assumed the road between Simcoe and Brantford as well as the road connecting Paris, Galt and Guelph as a new provincial highway. In addition, a concurrency was established with Highway 2 between Brantford and Paris. However, on June 4, 1930 a more direct routing between Brantford and Cambridge was established; the route between Paris and Cambridge was renumbered as Highway 24A. On September 9, 1936, the highway was extended south from Simcoe to Lake Erie then east to Highway 6 in Port Dover. This was followed several months later by an extension from Guelph through Erin to the Wellington–Peel county boundary, which was assumed on March 31, 1937. On August 11, 1937, the DHO designated the Shelburne to Collingwood Road as Highway 24, with the section to north of Singhampton displacing the historic Hurontario Street as the primary route due to rougher terrain along that road's course making it less desirable for a highway route. The highway turned east at Singhampton and continued to near Glen Huron, where it curved back north to rejoin Hurontario until its terminus in Collingwood. This left a large gap in the highway, including the terminus near Erin that did not end at a provincial highway. This was remedied eight months later when the DHO assumed several county roads in Peel County on April 13, 1938. This established Highway 24 between the county boundary and Orangeville, via Alton, as well as Highway 51 between Highway 10 in Caledon Village and Coulterville. In addition, Highway 10 and Highway 24 were signed concurrently between Orangeville and Shelburne. In 1965, the segment through Alton was redesignated as Highway 136 as Highway 24 was re-routed along a redesignated Highway 51 towards Highway 10 in that year.
Future
On September 12, 2006, it was announced that the Ontario provincial government would be undertaking a study to determine what improvements would be necessary to bring the highway up to current standards and to handle future growth. This study will focus on the portion of the highway between Cambridge and Brantford, where connections to Highways 401 and 403 exist, but suffer from extreme congestion during peak periods. Potential improvements/expansions include:
improving the road surface, lighting and traffic control devices at selected intersections
widening the road from two to four lanes near urban centres
complete expansion to a four-lane highway
construction of a multi-lane, controlled-access freeway