Historical Maps & Aerial Imagery
County atlases including townships of Markham and Vaughan (McGill University)
Patent plans recording Patents (part of granting) of Crown land (Archives of Ontario)
Tremaine map of York County, 1860 (University of Toronto Libraries)
Aerial images over Thornhill - ca.1930-1988. (Thornhill Archives)
YorkMaps - Find aerial and satellite imagery for York Region (including Thornhill) from 1954-present (York Region).
Built to Last: Heritage Properties from York County to York Region [Historical description of York County & York Region with maps] (York Region, 2017).
City of Toronto Aerial Images, 1947-1992 [many years of coverage extend into the Thornhill area].
York Region in 1860 vs Today - slide map (York Region)
York Region in 1970 vs Today - slide map (York Region)