| 1 | D&CI | Des Moines & Central Iowa R.R. | 7/1923-7/1936 | | NAKINA |
| 2 | D&CI | Des Moines & Central Iowa R.R. | 23-Jul | | NRHS |
| 3 | D&CI | DES MOINES & CENTRAL IOWA RAILROAD | | | PWRC |
| 4 | D&D | D & D Eisenbahngesellschaft mbH | Hagenow Land (D&D = Dehns und Dehns) | D | privat-bahn.de |
| 5 | D&H | Delaware and Hudson R.R. Corp. | 1/1941-10/1966 | | NAKINA |
| 6 | D&H | Delaware and Hudson R.R. Corp. | 1/52-10/66 | | NRHS |
| 7 | D&H | CANADIAN PACIFIC RAILWAY [DELAWARE & HUDSON RAILROAD CORP.] | | | PWRC |
| 8 | D&IM | Denver & Intermountain R.R. Co. | 8/1920-1/1946; 1/1952 | | NAKINA |
| 9 | D&IM | Denver & Intermountain R.R. Co. | 7/23-1/52 | | NRHS |
| 10 | D&IM | DENVER & INTERMOUNTAIN RAILROAD CORP. | | | PWRC |
| 11 | D&IR | (The) Duluth & Iron Range R.R. (Co.) | 8/1920-7/1954 | | NAKINA |
| 12 | D&IR | The Duluth & Iron Range R.R. Co. | 23-Jul | | NRHS |
| 13 | D&IR | Duluth & Iron Range R.R. | 4/38-1/52 | | NRHS |
| 14 | D&IR | DULUTH & IRON RANGE RAILROAD CO. | | | PWRC |
| 15 | D&M | Detroit & Mackinac Ry. | 8/1920-4/1961 | | NAKINA |
| 16 | D&M | Detroit & Mackinac Ry. | 7/23-4/61 | | NRHS |
| 17 | D&M | LAKE STATE RAILWAY CO. [DETROIT & MACKINAC RY] | | | PWRC |
| 18 | D&MM | (The) Dansville & Mount Morris R.R. (Co.) | 8/1920-4/1938 | | NAKINA |
| 19 | D&MM | The Dansville & Mount Morris R.R. Co. | 23-Jul | | NRHS |
| 20 | D&MM | Dansville & Mount Morris R.R. Co. | Apr-38 | | NRHS |
| 21 | D&MM | DANSVILLE & MT. MORRIS RAILROAD CO. | | | PWRC |
| 22 | D&N | Delaware & Northern Ry. | 1/1941 | | NAKINA |
| 23 | D&N | Delaware & Northern Ry. (Co.) | 7/1930-4/1938 | | NAKINA |
| 24 | D&N | Delaware & Northern R.R. Co. | 8/1920-7/1923 | | NAKINA |
| 25 | D&N | Delaware & Northern R.R. Co. | 23-Jul | | NRHS |
| 26 | D&N | Delaware & Northern R.R. | Apr-38 | | NRHS |
| 27 | D&N | *DELAWARE & NORTHERN RWY. | | | PWRC |
| 28 | D&N | *NEW YORK CENTRAL [DEXTER & NORTHERN RR] | | | PWRC |
| 29 | D&RG | Denver & Rio Grande Western R.R. Co. | 7/1932 | | NAKINA |
| 30 | D&RG | Denver & Rio Grande Western R.R. System | 7/1923 | | NAKINA |
| 31 | D&RG | Denver & Rio Grande Western R.R. System | 23-Jul | | NRHS |
| 32 | D&RG | DENVER & RIO GRANDE WESTERN RAILROAD | | | PWRC |
| 33 | D&RGW | Denver & Rio Grande Western R.R. (Co.) | 7/1930-10/1966 | | NAKINA |
| 34 | D&RGW | Denver & Rio Grande Western R.R. | 4/38-10/66 | | NRHS |
| 35 | D&RGW | DENVER & RIO GRANDE WESTERN RAILROAD | | | PWRC |
| 36 | D&S | DILLONVALE & SMITHFIELD RWY | | | PWRC |
| 37 | D&SL | Denver & Rio Grande Western R.R. | 4/1961-7/1965 | | NAKINA |
| 38 | D&SL | Denver & Salt Lake Ry. (Co.) | 8/1920-10/1957 | | NAKINA |
| 39 | D&SL | Denver & Salt Lake Ry. Co. | 23-Jul | | NRHS |
| 40 | D&SL | Denver & Salt Lake Ry. | 4/38-10/57 | | NRHS |
| 41 | D&SL | Denver & Rio Grande Western R.R. | 4/61-7/65 | | NRHS |
| 42 | D&SL | *DENVER & SALT LAKE rWY. CO. | | | PWRC |
| 43 | D&SL | *DENVER & RIO GRANDE WESTERN RAILROAD | | | PWRC |
| 44 | D&TS | Detroit & Toledo Shore Line R.R. (Co.) | 8/1920-4/1961 | | NAKINA |
| 45 | D&TS | Detroit & Toledo Shore Line R.R. Co. | 23-Jul | | NRHS |
| 46 | D&TS | Detroit & Toledo Shore Line R.R. | 4/38-4/61 | | NRHS |
| 47 | D&TS | DETROIT & TOLEDO SHORE LINE RAILROAD CO. | | | PWRC |
| 48 | D&W | Danville & Western Ry. | 4/1938-1/1950 | | NAKINA |
| 49 | D&W | Danville & Western Ry. Co. (Southern Ry. System) | 8/1920-7/1936 | | NAKINA |
| 50 | D&W | Danville & Western Ry. (Southern Ry. System) | 23-Jul | | NRHS |
| 51 | D&W | Danville & Western Ry. | Apr-38 | | NRHS |
| 52 | D&W | SOUTHERN RAILWAY {DANVILLE & WESTERN RAILWAY CO.} | | | PWRC |
