Vaughan is a city in Ontario, Canada. It is located in the Regional Municipality of York, just north of Toronto. Vaughan was the fastest-growing municipality in Canada between 1996 and 2006 with its population increasing by 80.2% during this time period and having nearly doubled in population since 1991. It is the fifth-largest city in the Greater Toronto Area, and the 17th-largest city in Canada.

Thornhill is a suburban district in the Regional Municipality of York in Ontario, Canada. The western portion of Thornhill is within the City of Vaughan and its eastern portion is within the City of Markham, with Yonge Street forming the boundary between Vaughan and Markham. Thornhill is situated along the northern border of Toronto, centred on Yonge, and is also immediately south of the City of Richmond Hill. Once a police village, Thornhill is still a postal designation. As of 2016, its total population, including both its Vaughan and Markham sections, was 112,719.