The Founding Of Thornhill Settlement began here after the opening of Yonge Street in the mid-1790's and by 1802 a grist-mill and sawmill were operating on the Don River. The community developed slowly until 1829 when Benjamin Thorne built a large flour mill, tannery and store. Within a year the village also contained a post-office named "Thornhill", a church, school and tavern. Thornhill's growth as a milling and agricultural centre suffered after 1846 when the loss of British markets drove Thorne out of business. Further decline occurred when the Northern Railway bypassed the community in 1853. Recovery began with the flow of grain southward during the American Civil War and by 1867 about 700 residents were recorded. From 1931 to 1971 Thornhill was an incorporated Police Village. Erected by the Ontario Heritage Foundation, Ministry of Culture and Recreation