| 1801 | SCOX | The Scoular Co. | 1/94; eliminated 10/99; 7/2000 | | NRHS |
| 1802 | SCOX | *SOUTHERN COTTON OIL CO. | | | PWRC |
| 1803 | SCOX | *SHIPPERS' CAR LINE, INC. [SCO TANK LINE, INC.] | | | PWRC |
| 1804 | SCOX | *SCOULAR CO. [SCOULAR BISHOP GRAIN COMPANY] | | | PWRC |
| 1805 | SCOX | Scoular Bishop Grain | | | RSRV |
| 1806 | SCOX | SCOULAR COMPANY, THE | | | SCAC4 |
| 1807 | SCOX | The Scoular Co. | | USA | TRAFFIC |
| 1808 | SCOY | SCOPE TRANSPORTATION | | | SCAC4 |
| 1809 | SCOZ | *CRAB ORCHARD & EGYPTIAN RAILROAD | | | PWRC |
| 1810 | SCOZ | *SPROUSE CREEK COAL CO. | | | PWRC |
| 1811 | SCOZ | Crab Orchard and Egyptian Railroad | | | RSRV |
| 1812 | SCOZ | CRAB ORCHARD & EGYPTIAN RAILROAD | | | SCAC4 |
| 1813 | SCOZ | Sprouse Creek Coal Company | | USA | TRAFFIC |
| 1814 | SCP | Scorpio Aviation | IATA: 8S, Callsign: Scorpio, | ET | AVCODES |
| 1815 | SCP | Helicopter.pl S.A. | Callsign: Sky Copter, | PL | AVCODES |
| 1816 | SCP | Scorpio | | | ICAO1 |
| 1817 | SCP | Mondi SCP, a.s. | | SK | VKM |
| 1818 | SCPA | ST CATHARINES PATTERN LIMITED | | | SCAC4 |
| 1819 | SCPB | SOUTH CAROLINA PUBLIC RAILWAYS COMMISSION | | | PWRC |
| 1820 | SCPC | SCHAMBER, PAUL | | | SCAC4 |
| 1821 | SCPF | SCOPE LOGISTICS LLC | | | SCAC4 |
| 1822 | SCPG | SCORPION AIR CARGO CORP | | | SCAC4 |
| 1823 | SCPH | SHOTCRETE PLUS | | | SCAC4 |
| 1824 | SCPK | PARKER, SCOTT TRUCKING COMPANY | | | SCAC3 |
| 1825 | SCPL | SEASCAPE LINES INC | | | SCAC4 |
| 1826 | SCPM | SCRAP MASTERS INC | | | SCAC4 |
| 1827 | SCPN | STYGA COMPANIA NAVIERA SA | | | SCAC4 |
| 1828 | SCPO | SCP TRANSPORT INC | | | SCAC4 |
| 1829 | SCPR | ST CHRISTOPHER TRUCKING INC | | | SCAC4 |
| 1830 | SCPS | SPECIAL EXPRESS | | | SCAC4 |
| 1831 | SCPT | SCHMIT, PAUL J TRUCKING INC | | | SCAC4 |
| 1832 | SCPU | SEACO SRL | | BDS | BIC |
| 1833 | SCPU | (SCXU) ALNERY NO. 954 LIMITED (U.K.) | | | PWRC |
| 1834 | SCPU | Alnery No. 954 Limited | | | RSRV |
| 1835 | SCPU | SEA CONTAINERS ASIA PTE LTD | | | SCAC4 |
| 1836 | SCPV | SISCO EXPRESS DELIVERY | | | SCAC4 |
| 1837 | SCPX | Shell Chemical Co., a Division of Shell Oil Co. | 7/1965-10/1966; eliminated 7/1969 | | NAKINA |
| 1838 | SCPX | Shell Oil Co. | added 7/1969; 4/1970-7/2005 | | NAKINA |
| 1839 | SCPX | Shell Chemical Co., a Division of Shell Oil Co. | 7/65-10/66; eliminated 7/69 | | NRHS |
| 1840 | SCPX | Shell Oil Co. | added 7/69; 4/70-7/2000 | | NRHS |
| 1841 | SCPX | *SUMMIT COUNTY PORT AUTHORITY | | | PWRC |
| 1842 | SCPX | +(SOEX) SHELL OIL COMPANY | | | PWRC |
| 1843 | SCPX | Shell Oil | | | RSRV |
| 1844 | SCPX | SHELL OIL COMPANY | | | SCAC4 |
| 1845 | SCPZ | SPROUSE CREEK PROCESS | | | PWRC |
| 1846 | SCQ | BF Scandinavian Aviation Academy AB | Callsign: Scavac, Name changed to OSM Aviation Academy AB. | S | AVCODES |
| 1847 | SCQ | OSM Aviation Academy AB | Callsign: Scavac, Name changed from BF Scandinavian Aviation Academy AB. | S | AVCODES |
| 1848 | SCQB | STONE CONSTRUCTION COMPANY | | | SCAC4 |
| 1849 | SCQC | SHARING CHRIST INC | | | SCAC4 |
| 1850 | SCQE | SCMC LOGISTICS LIMTED | | | SCAC4 |
| 1851 | SCQG | SOUTHERN CLASSIC CARRIERS INC | | | SCAC4 |
| 1852 | SCQH | SCANWELL CONTAINER LINE LTD | | | SCAC4 |
| 1853 | SCQI | STRANCO INC | | | SCAC4 |
| 1854 | SCQJ | S & | | | SCAC4 |
| 1855 | SCQK | STAR C TRUCKING, INC | | | SCAC1 |
| 1856 | SCQK | STAR C TRUCKING INC | | | SCAC4 |
| 1857 | SCQL | SCL LEMAN AG | | | SCAC4 |
| 1858 | SCQN | SUNCO CARRIERS INC ( LOGISTICS DIVI | | | SCAC4 |
| 1859 | SCQP | SCQ TRANSPORT | | | SCAC4 |
| 1860 | SCQU | SEA CONNECT UAB | | LT | BIC |
| 1861 | SCR | Si-Chang Flying Service Co., Ltd. | Callsign: Sichart, Ceased operations | T | AVCODES |
| 1862 | SCR | Silver Cloud Air GmbH | Callsign: Silver Cloud, | D | AVCODES |
| 1863 | SCR | Si-Chang Flying Service | | | ICAO1 |
| 1864 | SCR | SYDNEY COAL RAILWAY | | | PWRC |
| 1865 | SCR | Sydney Coal Railway | | | RSRV |
| 1866 | SCR | SYDNEY COAL RAILWAY | | | SCAC4 |
| 1867 | SCRD | SO COAST TRANS & DIST INC | | | SCAC4 |
| 1868 | SCRE | SCHAFER EXPRESS AND TRANSFER CO | | | SCAC1 |
| 1869 | SCRE | SCHAFER EXPRESS AND TRANSFER CO | | | SCAC4 |
| 1870 | SCRF | South Carolina Central R.R. Co., Inc. | added 4/1988; 1/1994-7/2005 | | NAKINA |
| 1871 | SCRF | South Carolina Central R.R. Co., Inc. | added 4/88; 1/94-7/2000 | | NRHS |
| 1872 | SCRF | SOUTH CAROLINA CENTRAL RAILROAD CO., INC. | | | PWRC |
| 1873 | SCRF | South Carolina Central Railroad | | | RSRV |
| 1874 | SCRF | SOUTH CAROLINA CENTRAL RAILROAD CO | | | SCAC4 |
| 1875 | SCRG | STREET CARTAGE LIMITED | | | SCAC4 |
| 1876 | SCRL | SCRAP METAL SERVICES LLC | | | SCAC4 |
| 1877 | SCRM | SEACOR MARINE LLC | | | SCAC4 |
| 1878 | SCRN | SUN COAST RESOURCES INC | | | SCAC4 |
| 1879 | SCRO | SAUCIER, PIERRE TRANSPORT INC | | | SCAC4 |
| 1880 | SCRP | S C TRANSPORT | | | SCAC4 |
| 1881 | SCRQ | SCORE | | | SCAC4 |
| 1882 | SCRT | SACRAMENTO COUNTY REGIONAL TRANSIT DISTRICT | | | PWRC |
| 1883 | SCRTD | Southern California Regional Transit District | | USA | TRAFFIC |
| 1884 | SCRU | SEACROSS SHIPPING LLP | | IND | BIC |
| 1885 | SCRU | STAR CONTAINER SERVICES | | | SCAC4 |
| 1886 | SCRW | SEAWAY COMMERCIAL RAILWAY | | | PWRC |
| 1887 | SCRW | Seaway Commercial Railway | | | RSRV |
| 1888 | SCRW | SCHERME | | | SCAC4 |
| 1889 | SCRX | Susquehanna Chemical Corp. | 4/1947; 1/1950 (not listed) | | NAKINA |
| 1890 | SCRX | Santa Clarita Railway d/b/a James Clark & Co. | 7/2000 (not listed) | | NAKINA |
| 1891 | SCRX | South Carolina Public Railways | 7/2005 | | NAKINA |
| 1892 | SCRX | Santa Clarita Railway d/b/a James Clark & Co. | Jul-00 | | NRHS |
| 1893 | SCRX | *SUSQUEHANNA CHEMICAL CORP. | | | PWRC |
| 1894 | SCRX | *SANTA CLARITA RAILWAY, DBA JAMES CLARK & COMPANY | | | PWRC |
| 1895 | SCRX | *SCHUYLKILL COUNTY RAIL AUTHORITY | | | PWRC |
| 1896 | SCRX | +SOUTH CAROLINA PUBLIC RAILWAYS | | | PWRC |
| 1897 | SCRX | Santa Clarita Railway (James Clark and) | | | RSRV |
| 1898 | SCRX | SOUTH CAROLINA PUBLIC RAILWAYS | | | SCAC4 |
| 1899 | SCRY | SOUTH CENTRAL RECYCLING | | | SCAC4 |
| 1900 | SCRZ | SQUAW CREEK COAL COMPANY | | | PWRC |
