The L&NWR owned the railway and at first provided its locomotives and rolling stock, with the locomotives coming from its Crewe Works. The railway passed to the London, Midland and Scottish Railway in 1923 but an agreement was reached in 1933 for the line to be worked by the Great Northern Railway. Because the partition of Ireland placed an international frontier across the DN&G's Greenore – Newry line, it was not absorbed into either the Great Southern Railways in 1925 or the Ulster Transport Authority in 1948.
