Union Mills Homestead Historic District is a national historic district at Westminster, Carroll County, Maryland, United States. It comprises a dwelling house, a grist mill, and a Bollman-design bridge. The Shriver Homestead was built in 1797 by Andrew and David Shriver and has been continually occupied by the family. The mill, also built 1797, is a large brick structure, built of locally manufactured brick laid in both Flemish bond and common bond. On June 30, 1863, General J.E.B.