A mill town on the Patapsco with its own post office until 1971
A ghost town straddling the Patapsco east of Woodstock and north of old Ellicott City, in both Baltimore and Howard counties at once. The mill is the reason it existed and the reason anything is left: Daniels Mill is on the National Register. The post office ran from March 1943 until August 1971, which gives you the shape of the place better than most dates could, a working community with its own address that simply stopped needing one.
Other places on the map within a couple of hours of here.