The numbered roads in the Regional Municipality of Durham account for about 832 kilometres (517 mi) of the county road system in the Canadian province of Ontario. The Durham Region Works Department owns and maintains the regional roads and regional highways, while the Ministry of Transportation of Ontario (MTO) owns and maintains the King's Highways in the region. The 67 (7 King's Highways, 4 Regional Highways, and 56 Regional Roads) numbered roads[note 1] provide access to the entirety of the region. Highway 401 forms the backbone of the region, traveling from the western boundary of the region to the eastern boundary alongside Lake Ontario, and serving over 200,000 vehicles per day. Several provincially maintained highways existed in the region prior to 1998, when they were transferred to municipal government in the region as part of a province-wide downloading of highways. Where the regional tier of municipal government has since been responsible for these routes, they have been designated as Durham Regional Highways.
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