Unionville is an unincorporated community in Frederick County, Maryland, United States. It is located approximately halfway between Frederick and Westminster, just east of Libertytown off of MD Route 26 (Liberty Road). Pearre-Metcalfe House was listed on the National Register of Historic Places in 1979.
Unionville is recognized as having experienced the world record amount of rain in a one minute period: 31.2 mm (1.23 in) on 4 July 1956.
Coordinates: 39°28′29″N 77°11′08″W / 39.47472°N 77.18556°W