| 1 | SOO | Southern Air, Inc. | IATA: 9S, Callsign: Southern Air, IATA Prefix: 099, AOC merged into Atlas Air, Inc. (5Y/GTI) w.e.f. 17 November 2021. | USA | AVCODES |
| 2 | SOO | Southern Air | | | ICAO1 |
| 3 | SOO | Minneapolis, St. Paul & Sault Ste. Marie Ry. Co. | 8/1920-4/1961 | | NAKINA |
| 4 | SOO | Soo Line R.R. Co. | 7/1965-7/2005 | | NAKINA |
| 5 | SOO | Minneapolis, St. Paul & Sault Ste. Marie Ry. Co. | 4/38-4/61 | | NRHS |
| 6 | SOO | Soo Line R.R. Co. | 7/65-7/2000 | | NRHS |
| 7 | SOO | CANADIAN PACIFIC RWY. [SOO LINE RAILROAD; MINNEAPOLIS, ST. PAUL & SAULT STE. MARIE RR] | | | PWRC |
| 8 | SOO | Soo Line Railroad (Canadian Pacific Railway) | | | RSRV |
| 9 | SOO | SOO LINE RAILROAD | | | SCAC4 |
| 10 | SOO | Soo Line Railroad | | USA | TRAFFIC |
| 11 | SOOA | SOUTHERN CROSS CORPORATION | | | SCAC4 |
| 12 | SOOC | SCHOOL OF OCEANOGRAPHY UNIVERSITY O | | | SCAC4 |
| 13 | SOOG | SOURDOUGH TRANSFER INC | | | SCAC4 |
| 14 | SOOL | SOOLINE CATTLE COMPANY | | | SCAC4 |
| 15 | SOON | SOONER ENT LTD | | | SCAC4 |
| 16 | SOOP | SLOOP INC | | | SCAC4 |
| 17 | SOOQ | SOUTHERN OIL TRANSPORT LLC | | | SCAC4 |
| 18 | SOOS | SOO SINGAPORE JERKY LTD | | | SCAC4 |
| 19 | SOOV | SOO VAN & STORAGE | | | SCAC4 |
| 20 | SOOY | SAVE-ON OIL COMPANY INC | | | SCAC4 |
| 21 | SOOZ | CANADIAN PACIFIC RWY. [SOO LINE RAILROAD; MINNEAPOLIS, ST. PAUL & SAULT STE. MARIE RR] | | | PWRC |
| 22 | SOOZ | Soo Line Railroad (Canadian Pacific Railway) | | | RSRV |
| 23 | SOOZ | SOO LINE RAILROAD | | | SCAC4 |
