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. Stuart of the Confederate Army of Northern Virginia camped at Union Mills and was hosted by part of the Shriver family. On the following day, General James Barnes of the 5th Corps of the Army of the Potomac arrived on the site and welcomed and entertained by other members of the family.