| 6101 | SLER | SOUTHLAND EXPRESS INC | | | SCAC4 |
| 6102 | SLES | STARLIGHT EXPRESS INC | | | SCAC4 |
| 6103 | SLEU | SPINNAKER EQUIPMENT SERVICES INC. | | USA | BIC |
| 6104 | SLEU | JSC SIBLENATRANS-EXPEDITION | | | SCAC4 |
| 6105 | SLEV | SOUTHWEST LOGISTICS SERVICES | | | SCAC4 |
| 6106 | SLEX | Short Line Enterprises, Ltd. | 1/1994-7/2005 (not listed) | | NAKINA |
| 6107 | SLEX | Short Line Enterprises, Ltd. | 1/94-7/2000 | | NRHS |
| 6108 | SLEX | SHORT LINE ENTERPRISES, LTD. (FILMORE & WESTERN) | | | PWRC |
| 6109 | SLEX | Short Line Enterprises Limited | | | RSRV |
| 6110 | SLEX | SHORT LINE ENTERPRISES, LTD. | | | SCAC4 |
| 6111 | SLF | Skyline Flights GmbH | Callsign: Skyship, | D | AVCODES |
| 6112 | SLF | StarFly Helicopters | | I | AVCODES |
| 6113 | SLF | Silver Bird Charterflug GmbH | Callsign: Silver Fox, | D | AVCODES |
| 6114 | SLF | Starfly | | | ICAO1 |
| 6115 | SLFB | SL EXPRESS | | | SCAC4 |
| 6116 | SLFD | SHINN LOGISTICS LLC | | | SCAC4 |
| 6117 | SLFF | STAR ALFALFA INC | | | SCAC4 |
| 6118 | SLFG | SOLIS FREIGHT | | | SCAC4 |
| 6119 | SLFI | SEALIFT INC | | | SCAC4 |
| 6120 | SLFJ | SMT LOGISTICS | | | SCAC4 |
| 6121 | SLFM | SCHELL FARMS LTD | | | SCAC4 |
| 6122 | SLFN | SEA LAND ENERGY OF MAINE | | | SCAC4 |
| 6123 | SLFP | SUMMIT LIFT COMPANY LTD | | | SCAC4 |
| 6124 | SLFQ | SMALL FARMS LLC | | | SCAC4 |
| 6125 | SLFR | SHOWA LINE, LTD. | | | PWRC |
| 6126 | SLFR | SEA-LAND MOTOR FREIGHT, INC | | | SCAC1 |
| 6127 | SLFS | St. Louis-San Francisco Ry. Co. | 8/1920 | | NAKINA |
| 6128 | SLFS | ST. LOUIS-SAN FRANCISCO RWY. CO. | | | PWRC |
| 6129 | SLFS | SEA LION OCEAN FREIGHT | | | SCAC4 |
| 6130 | SLFT | SEALIFT NV | | | SCAC4 |
| 6131 | SLFU | SUNLIT FLUO & CHEMICAL CO., LTD. | | RC | BIC |
| 6132 | SLFU | SHOWA LINE, LTD. | | | PWRC |
| 6133 | SLFU | Showa Line Limited | | | RSRV |
| 6134 | SLFV | SAN LUIS INTERNATIONAL FREIGHT SERV | | | SCAC4 |
| 6135 | SLFY | SHUR-LOC FABRIC SYSTEM | | | SCAC4 |
| 6136 | SLG | Saskatchewan Government Air Ambulance Service | Callsign: Lifeguard, | CDN | AVCODES |
| 6137 | SLG | Saskatchewan Government | | | ICAO1 |
| 6138 | SLG | Spitzke Logistik GmbH | Großenbeeren | D | privat-bahn.de |
| 6139 | SLG | Spitzke Logistik GmbH | | DE | VKM |
| 6140 | SLGB | STALLINGS BROS INC | | | SCAC4 |
| 6141 | SLGF | SCHLAUGIES FUEL OIL SERVICE INC | | | SCAC4 |
| 6142 | SLGG | Sidney & Lowe R.R., Inc. | added 10/1983; eliminated 4/1989; eliminated 4/1991; added 7/1992; 1/1994; eliminated 4/1997 | | NAKINA |
| 6143 | SLGG | Progress Rail Services Corp. d/b/a Sidney & Lowe R.R., Inc. | added 4/1997; 7/2000-7/2005 | | NAKINA |
| 6144 | SLGG | Sidney & Lowe R.R., Inc. | added 10/83; eliminated 4/89; eliminated 4/91; added 7/92; 1/94; eliminated 4/97 | | NRHS |
| 6145 | SLGG | Progress Rail Services Corp. d/b/a Sidney & Lowe R.R., Inc. | added 4/97; 7/2000 | | NRHS |
| 6146 | SLGG | PROGRESS RAIL SERVICES CORP. d/b/a SIDNEY & LOWE RAILROAD, INC. | | | PWRC |
| 6147 | SLGG | Sidney and Lowe Railroad | | | RSRV |
| 6148 | SLGG | SIDNEY & LOWE RAILROAD | | | SCAC4 |
| 6149 | SLGG | Sidney & Lowe | | USA | TRAFFIC |
| 6150 | SLGJ | STERLING LG SOLUTIONS | | | SCAC4 |
| 6151 | SLGK | SELECT LOGISTICS NETWORK INC | | | SCAC4 |
| 6152 | SLGM | SATTERWHITE LOG HOMES | | | SCAC4 |
| 6153 | SLGO | STERLING CORPORATION | | | SCAC4 |
| 6154 | SLGQ | SECA LOGISTICS LLC | | | SCAC4 |
| 6155 | SLGR | STAR LOGISTICS GROUP INC | | | SCAC4 |
| 6156 | SLGS | SOURCE LOGISTICS INC | | | SCAC4 |
| 6157 | SLGT | STEEL LOGISTICS INC | | | SCAC4 |
| 6158 | SLGW | Salt Lake, Garfield and Western Ry. Co. | 1/1975-1/1980; eliminated 4/1989; 1/1994-7/2005 | | NAKINA |
| 6159 | SLGW | Salt Lake, Garfield and Western Ry. Co. | 1/75-1/80; eliminated 4/89; 1/94-7/2000 | | NRHS |
| 6160 | SLGW | SALT LAKE, GARFIELD & WESTERN RWY. | | | PWRC |
| 6161 | SLGW | Salt Lake, Garfield and Western Railway | | | RSRV |
| 6162 | SLGX | St. Louis County Gas Co. | 7/1923 | | NAKINA |
| 6163 | SLGX | Louis E. & Simon Seley | 1/1941 | | NAKINA |
| 6164 | SLGX | *ST. LOUIS COUNTY GAS CO. | | | PWRC |
| 6165 | SLGX | *LOUIS E. & SIMON SELEY | | | PWRC |
| 6166 | SLGY | SHERIDAN LIGHTING SYSTEMS INC | | | SCAC4 |
| 6167 | SLH | Silverhawk Aviation, Inc. | Callsign: Silverhawk, | USA | AVCODES |
| 6168 | SLH | Silverhawk Aviation | | | ICAO1 |
| 6169 | SLH | St. Louis & Hannibal Ry. | 1/1941-7/1954 | | NAKINA |
| 6170 | SLH | St. Louis & Hannibal Ry. | Jan-52 | | NRHS |
| 6171 | SLH | *ST. LOUIS & HANNIBAL RWY. | | | PWRC |
| 6172 | SLH | *SUGARLOAF & HAZLETON RAILROAD | | | PWRC |
| 6173 | SLH | Sugarloaf and Hazelton Railroad | | | RSRV |
| 6174 | SLHA | SLASHING CARROLL & KENNY LTD | | | SCAC4 |
| 6175 | SLHC | STANDLEE HAY CO INC | | | SCAC4 |
| 6176 | SLHD | SMITH, L & H FRUIT CO LIMITED | | | SCAC4 |
| 6177 | SLHE | STEEL HORSE TRANSPORTATION INC | | | SCAC4 |
| 6178 | SLHG | SILHOUETTE SHIPPING LTD | | | SCAC4 |
| 6179 | SLHI | SUMMIT LOGISTICS INTERNATIONAL | | | SCAC4 |
| 6180 | SLHK | STARLIGHT EXPRESS COACHES INC | | | SCAC4 |
| 6181 | SLHL | STEMCELL TECHNOLOGIES INC | | | SCAC4 |
| 6182 | SLHN | SALATHE OIL CO INC | | | SCAC4 |
| 6183 | SLHO | SLH TRANSPORT INC | | | SCAC4 |
| 6184 | SLHR | SALH TRUCKING (2001) LTD | | | SCAC4 |
| 6185 | SLHT | SHOWA LINE, LTD. | | | PWRC |
| 6186 | SLHT | SILHOUET-TONE | | | SCAC4 |
| 6187 | SLHU | SEA LLOYD SHIPPING LINES PTE LTD | | SGP | BIC |
| 6188 | SLHU | SHOWA LINE, LTD. | | | PWRC |
| 6189 | SLHU | Showa Line Limited | | | RSRV |
| 6190 | SLHU | TRANSAMERICA LEASING INC | | | SCAC4 |
| 6191 | SLHX | SIOUXLAND HISTORICAL RAILROAD | | | PWRC |
| 6192 | SLHY | SCHUGEL LOGISTICS INC | | | SCAC4 |
| 6193 | SLI | Aerolitoral S.A. de C.V. | IATA: 5D, Callsign: Costera, IATA Prefix: 642, Name changed to Aerolitoral, S.A. de C.V., d/b/a Aerom�xico Connect. Designator 5D reinstated by IATA | MEX | AVCODES |
| 6194 | SLI | Aerolitoral, S.A. de C.V., d/b/a Aeroméxico Connect | IATA: 5D, Callsign: Costera, IATA Prefix: 642, Name changed from Aerolitoral S.A. de C.V. Designator 5D reinstated by IATA | MEX | AVCODES |
| 6195 | SLI | Aerolitoral | IATA: 5D | | ICAO1 |
| 6196 | SLIA | SEA SHIPPING LINE (CALIFORNIA) INC | | | SCAC4 |
| 6197 | SLIB | SILICON LOGISTICS INC | | | SCAC4 |
| 6198 | SLIC | SHELMAN, LARIS & SONS TRUCKING INC | | | SCAC4 |
| 6199 | SLIH | SANTANGELO LIGHTING | | | SCAC4 |
| 6200 | SLIJ | STREAMLINE LLC | | | SCAC4 |
