| 1 | SDI | Servicios Dinamicos De Aviacion, S.A. De C.V. | Callsign: Servi Dinamic, | MEX | AVCODES |
| 2 | SDID | SOUTHPOINT DISTRIBUTING INC (N/K/A | | | SCAC4 |
| 3 | SDIF | SUPERIOR DELIVERY INC | | | SCAC4 |
| 4 | SDIG | STANDINGER S A DE C V | | | SCAC4 |
| 5 | SDIH | SOUTHSHORE DISTRIBUTION INC | | | SCAC4 |
| 6 | SDIK | SKYCO DISTRIBUTION INC | | | SCAC4 |
| 7 | SDIM | SCHUMM, DAVID INC | | | SCAC4 |
| 8 | SDIQ | SD INCORPORATED | | | SCAC4 |
| 9 | SDIS | STANDISH TRANSPORT | | | SCAC4 |
| 10 | SDIT | San Diego & Imperial Valley Ry. Co. | added 10/1984 | | NAKINA |
| 11 | SDIT | San Diego & Imperial Valley Ry. Co. | added 10/84 | | NRHS |
| 12 | SDIT | SAN DIEGO & IMPERIAL VALLEY RWY. CO. | | | PWRC |
| 13 | SDIT | SEDITA TRUCKING INC | | | SCAC4 |
| 14 | SDIV | SAN DIEGO & IMPERIAL VALLEY RAILROAD (EXPIRED) | | | PWRC |
| 15 | SDIV | San Diego and Imperial Valley Railroad | | | RSRV |
| 16 | SDIV | SPECIAL DISTRIBUTION SERVICES INC | | | SCAC4 |
| 17 | SDIW | SHEPPARDWOOD DISTRIBUTORS | | | SCAC4 |
| 18 | SDIX | Smith-Douglass Co., Inc. | 4/1947-7/1954; eliminated 4/1957 | | NAKINA |
| 19 | SDIX | Steel Dynamics, Inc. | 7/2005 (not listed) | | NAKINA |
| 20 | SDIX | Smith-Douglass Co., Inc. | 1/52; eliminated 4/57 | | NRHS |
| 21 | SDIX | *SMITH-DOUGLAS CO., INC. | | | PWRC |
| 22 | SDIX | *SOUTH DAKOTA & IOWA RAILROAD | | | PWRC |
| 23 | SDIX | +STEEL DYNAMICS, INC. | | | PWRC |
| 24 | SDIX | STEEL DYNAMICS INC | | | SCAC4 |
| 25 | SDIY | San Diego & Imperial Valley R.R. Co. | eliminated 10/1992; 1/1994-7/2005 | | NAKINA |
| 26 | SDIY | San Diego & Imperial Valley R.R. Co. | eliminated 10/92; 1/94-7/2000 | | NRHS |
| 27 | SDIY | SAN DIEGO & IMPERIAL VALLEY RAILROAD CO.,INC. | | | PWRC |
| 28 | SDIY | San Diego and Imperial Valley Railroad | | | RSRV |
| 29 | SDIY | SAN DIEGO AND IMPERIAL VALLEY RAILROAD | | | SCAC1 |
| 30 | SDIY | SAN DIEGO & IMPERIAL VALLEY RAILROA | | | SCAC4 |
| 31 | SDIY | San Diego & Imperial Valley | | USA | TRAFFIC |
