Thornhill is a town in the Mid Nithsdale area of Dumfries and Galloway, Scotland, south of Sanquhar and north of Dumfries on the main A76 road. Thornhill sits in the Nithsdale valley with the Carsphairn and Scaur range to the west and the Lowther hills to the east. It was initially a small village, planned and built in 1717 on the Queensberry Estate on the road linking Dumfries to Glasgow.
The town is primarily comprised a grid pattern with the main street of Drumlanrig Street (the A76), East and West Morton Streets, New Street, Townhead Street and Gill Road (the A702).
The town is near Drumlanrig Castle, a 17th-century turreted mansion once the ancient Douglas stronghold, now home to the Duke of Buccleuch and Queensberry.
The most recently published Census data from 2001 puts the population at 1,512 inhabitants.
Until 1975 Thornhill was located in the parish of Morton in Dumfriesshire in Scotland.
Refer to the parish of Morton