The boundary increase expands the original historic district by ten acres containing fifteen buildings, 209 structures, and one object (source NRHP website).

Because the digitized nomination form is not yet available from NPS Focus, I have no details about the the buildings and structures.

The Denver & Rio Grande Railroad San Juan Extension originally became an NRHP Historic District in 1973 and was listed in three counties: Conejos, Archuleta and Rio Arriba.