 MD 231 enters Calvert County at Hallowing Point and continues east as Hallowing Point Road, passing an industrial park and Hallowing Point Park.After intersecting MD 508 (Adelina Road), the state highway veers northeast through the village of Barstow, where the highway passes west of a park and ride lot and the Calvert County Fairgrounds before it intersects Barstow Road, which serves the historic homes Cedar Hill and Willow Glenn.MD 231 passes the Prince Frederick campus of the College of Southern Maryland before entering Prince Frederick.