In the south, between Dundas Street and Lakeshore Road
Halton Region shares jurisdiction with the Region of Peel over segments of the road along the Halton-Peel boundary between Highway 407 and Mayfield Road and designates it as Halton Regional Road 19,[2] although only Peel Road 19 signs are posted. The Town of Halton Hills shares jurisdiction with the Region of Peel over the segments along the Halton-Peel boundary between Mayfield Road and 32 Sideroad. Wellington County shares jurisdiction with the Region of Peel over the segment between 32 Sideroad and Beech Grove Sideroad, and designates it as Wellington County Road 25. The remaining northerly segment between Beech Grove Sideroad and East Garafaxa-Caledon Townline is under joint jurisdiction between the Town of Caledon, Town of Erin and Township of East Garafraxa, where Winston Churchill forms the boundary between any two of these municipalities. The segment between Highway 407 and Dundas Street is entirely within Peel Region (the region line is shifted west to Highway 407 and 9th Line), and is under the jurisdiction of the City of Mississauga. Formerly, this section also formed the divisional boundary, but was changed due to municipal restructuring in 1974 resulting in transferring of the lands to the west to Mississauga.[3]
In the community of Norval, Winston Churchill Boulevard deviates westward to be situated entirely within Halton Region and is known as Adamson Street. Despite this, it is still signed exclusively as Peel Regional Road 19.
Within Terra Cotta, Winston Churchill deviates eastward to be situated entirely within the Town of Caledon. It is concurrent with Peel Regional Road 9 (King Street) for approximately 550 metres.
