..I'm stumped. Cheif Troll might be right, running in reverse because it didn't telescope train nor climb atop. Place if the fun part, though. Line west of Morristown to Dover Jct via Rockaway was not double tracked until '03 or '05 when westbound service was sent west at the present station site rather than through Rockaway although the brance remained single track. Sussex Branch is a good guess, too, as is the P&D. Engine was origonally #88 out on the Buffalo Division before 1899, the #159 then #641 from '99 ton '19 scrapping. So that leaves the Syrause, Utica or Ithaca branches are possiblities, too. But, because Great Uncle was from Morristown it is more likely NJ somewhere. Did he work for the railroad or just happened to have this pic? Since all the books I have do not reveal anything, newpaper archives or railroad records are the next phase and I ain't handy to any of them. Good Luck.