| 1 | NTR | TNT International Aviation | Callsign: Nitro, | GB | AVCODES |
| 2 | NTR | SAS Natireva t/a Air Moana | IATA: NM, | PF | AVCODES |
| 3 | NTR | TNT International Aviation | | | ICAO1 |
| 4 | NTR | Mississippi Central R.R. Co. | added 4/1994; 7/2000; eliminated 10/2001; 7/2005 | | NAKINA |
| 5 | NTR | Natchez Trace R.R. | added 4/1982; 1/1994; eliminated 4/1994 | | NAKINA |
| 6 | NTR | Natchez Trace R.R. | added 4/82; 1/94; eliminated 4/94 | | NRHS |
| 7 | NTR | Mississippi Central R.R. Co. | added 4/94; 7/2000 | | NRHS |
| 8 | NTR | (MSCI) MISSISSIPPI CENTRAL RAILROAD CO. [NATCHEZ TRACE RR] | | | PWRC |
| 9 | NTR | Natchez Trace Railroad (Mississippi Central Railroad) | | | RSRV |
| 10 | NTRA | NORTHERN TRANSPORT INC | | | SCAC3 |
| 11 | NTRA | NATIONAL TRUCKERS ALLIANCE | | | SCAC4 |
| 12 | NTRB | NORTHERN TRAVEL BUREAU | | | SCAC3 |
| 13 | NTRC | NATIONAL RECYCLING CORP | | | SCAC4 |
| 14 | NTRD | NAPLES TRANSPORT | | | SCAC4 |
| 15 | NTRE | NOTRE LINES INC | | | SCAC3 |
| 16 | NTRE | NORTHERN TRAILER | | | SCAC4 |
| 17 | NTRG | NATIONAL TRUCKING INC | | | SCAC3 |
| 18 | NTRG | NOVA TRANSPORT | | | SCAC4 |
| 19 | NTRI | NEWMAN TRUCKING INC | | | SCAC3 |
| 20 | NTRL | NORMANS TRANSFER LIMITED | | | SCAC3 |
| 21 | NTRM | NEUMANN TRUCKING | | | SCAC4 |
| 22 | NTRN | NASH TRUCKING | | | SCAC3 |
| 23 | NTRO | NITRO EXPRESS CORPORATION | | | SCAC4 |
| 24 | NTRP | NEW (TRANS) PORT INC | | | SCAC3 |
| 25 | NTRQ | NILE TRANSPORT | | | SCAC4 |
| 26 | NTRR | NIGHTRUNNERS TRANSPORT LTD | | | SCAC4 |
| 27 | NTRS | NATIONAL TRANSPORTATION SERVICE INC | | | SCAC3 |
| 28 | NTRT | NOTTESTAD TRUCKING | | | SCAC4 |
| 29 | NTRU | ICOOL CHEMICAL CO., LTD. | | PRC | BIC |
| 30 | NTRX | NTL Transportation Ltd. | added 10/2003; 7/2005 | | NAKINA |
| 31 | NTRX | NTL Transportation Corp. | added 10/2001; eliminated 10/2003 | | NAKINA |
| 32 | NTRX | Nortex Refining Co. (Skelly Oil Co.) | 7/1923 | | NAKINA |
| 33 | NTRX | *SKELLY OIL CO. {NORTEX REFINING CO.] | | | PWRC |
| 34 | NTRX | +NTL TRANSPORTATION CORP. | | | PWRC |
| 35 | NTRX | NTL Transportation Corporation | | | RSRV |
| 36 | NTRX | NTL TRANSPORTATION LTD | | | SCAC4 |
| 37 | NTRY | Nimishillen & Tuscarawas L.L.C. | added 4/2000; 7/2000-7/2005 | | NAKINA |
| 38 | NTRY | Nimishillen & Tuscarawas Ry. Co. | added 4/1990; 1/1994; eliminated 4/2000 | | NAKINA |
| 39 | NTRY | Nimishillen & Tuscarawas Ry. Co. | added 4/90; 1/94; eliminated 4/2000 | | NRHS |
| 40 | NTRY | Nimishillen & Tuscarawas L.L.C. | added 4/2000; 7/2000 | | NRHS |
| 41 | NTRY | NIMISHILLEN & TUSCARAWAS RAILWAY CO. | | | PWRC |
| 42 | NTRY | Nimishillen and Tuscarawas | | | RSRV |
| 43 | NTRY | NIMISHILLEN & TUSCARAWAS RAILWAY CO | | | SCAC3 |
| 44 | NTRY | NIMISHILLEN & TUSCARAWAS LLC | | | SCAC4 |