The Derby line Border Station occupies a 68,431 square foot site on the west side of U.S. Route 5, or Main Street, several hundred feet south of the Canadian border. The border station is a major visual element in the center of the village of Derby Line, located next the the village hall and across from a mixed residential and commercial block. The Canadian border station, located on the east side of the highway beyond a bridge, is not visible from the station. The site is relatively level adjacent to the building, with a downward slope toward the west at the western edge of the property. A free-standing garage and inspection building, located along the southern edge of the property behind the station building, was part of the original development. A free-standing livestock inspection station, which appears to have been constructed in the 1950s, is located to the west of the station building.
As originally developed, the inspection station occupied the eastern edge of the site, with a four-lane canopy projecting over a concrete driveway below, bordered by a gravel drive adjacent to the road. Another gravel drive along the south of the building serviced the garage and inspection station. Concrete curbing bordered the outer edges of the gravel drive. Most of the site to the west, which was originally grass, is paved adjacent to the buildings.
This handsome Georgian revival building, constructed in 1931–1932, is a large, hip roofed, two-story brick structure with a wooden canopy projecting from the east facade and several small, later additions at the rear, or west, facade. The original core is a symmetrical brick block measuring seven bays wide by three bays deep. Window wells along the south facade and a large areaway along the west facade, both of which have been closed off, originally provided daylight to the basement. Entry is made up one-half step to the first floor at the center bay of the east facade, up two steps to the same level through doors in the east bays of the north and south facades, and by a low loading dock on the west facade. A pedestrian entrance on the west facade is entered at grade from the exterior onto an intermediate landing in the stairwell between the first floor and basement.
The interiors of original public and private spaces within the core are consistently simple, functional and non-monumental in character. The first floor has been extensively renovated. Most original plans, volumes and finishes survive intact on the second floor and basement. Public offices of Immigration and Customs occupy the south half of first floor, and the Post Office occupies the north half of the first floor. A stair hall, approached by an original corridor bi-secting the building, leads to the basement and second floors. The second floor contains additional administrative offices, formerly public toilets now used by staff, several former detention and interrogation cells now unused. Second floor spaces are arranged around a long, double-loaded corridor approached by the staircase. The basement, which was originally used for detention, storage and mechanical space, is primarily used for the latter functions.
Except where noted below in the descriptions of zones, interior finishes are standardized throughout. Concrete beams are exposed throughout the interior ceilings, carried by exposed piers. Walls and ceilings are typically finished with smooth painted gypsum plaster. A plain, bead-moulded chair rail and ogee-molded picture rails are used on the walls of public areas and offices. Painted wood baseboards are typically comprised of a quarter round shoe mold, and a two-part fascia washboard surmounted by a running cyma reversa mold. Doorways typically contain painted wood doors with five horizontal panels or two horizontal panels below a glazed panel, enframed within a running molded surround comprised of two flat fascia planes bordered with a deep cyma reversa mold along the interior edge, and a flat cyma recta mold at the perimeter. Some enframements contain operable glazed hopper transoms. Doors are hung with brass hinges, and operated with brass knobs with inset cylinder locks. Windows are enframed with simple running molded surrounds terminating in projecting bullnose stools. Original lighting fixtures have been systematically replaced with ceiling-surface mounted fluorescent units. Most floors are finished with non-original wall-to-wall carpet.