Any of the stereoviews marked as C.P.R.R (Hart/Watkins) are those featured in the Stereo Views of C.P.R.R. - the official photos documenting the building of the Central Pacific Railroad's leg of the Transcontinental Railroad, starting at Sacramento, CA an making its way east through the Sierra Nevada Mountains.

Alfred A. Hart was the official photographer of the western half of the first transcontinental railroad, for which he took 364 historic stereoviews of the railroad construction in the 1860s.