The Regional Municipality of Durham, informally referred to as Durham Region, is a regional municipality in Southern Ontario, Canada. Located east of Toronto and the Regional Municipality of York, Durham forms the east-end of the Greater Toronto Area and part of the Golden Horseshoe region. It has an area of approximately 2,500 km2 (970 sq mi). The regional government is headquartered in Whitby.

The Pickering Airport Lands are parcels of lands owned by the Government of Canada located in York Region and Durham Region in the Greater Toronto Area of Ontario. The lands, totaling approximately 18,600 acres and located approximately 56 kilometres east of Downtown Toronto, were expropriated in 1972 by the federal government intending for a second international airport to serve the city of Toronto, its metropolitan area, and the surrounding Golden Horseshoe region. Since then, the federal government has leased the lands to private tenants and allocated more than half to form the Rouge National Urban Park.