| 1 | NI | Lineas Aereas Nicaragus, S.A. | Callsign: Lanica, Name changed to Aeronica, Aerolineas Nicaraguenses S.A. | NIC | AVCODES |
| 2 | NI | Aeronica, Aerolineas Nicaraguenses S.A. | ICAO: ANI, Callsign: Aeronica, Name changed from Lineas Aereas Nicaragus | NIC | AVCODES |
| 3 | NI&M | New Iberia & Northern R.R. Co. | 4/1938 | | NAKINA |
| 4 | NI&M | New Iberia & Northern R.R. Co. (Gulf Coast Lines) | 7/1932 | | NAKINA |
| 5 | NI&M | New Iberia & Northern R.R. Co. | Apr-38 | | NRHS |
| 6 | NI&M | NEW IBERIA & NORTHERN RAILROAD CO. | | | PWRC |
| 7 | NI&N | New Iberia & Northern R.R. Co. (Gulf Coast Lines) | 8/1920-7/1936 | | NAKINA |
| 8 | NI&N | NEW IBERIA & NORTHERN RAILROAD CO. | | | PWRC |
| 9 | NIA | Nordavia Fluggesellschaft mbH | Callsign: Nordavia, | D | AVCODES |
| 10 | NIA | Nile Air | IATA: NP, Callsign: Hapi Air, ICAO callsign changed to Nile Bird | ET | AVCODES |
| 11 | NIA | Nile Air | IATA: NP, Callsign: Nile Bird, ICAO callsign changed from Hapi Air | ET | AVCODES |
| 12 | NIAC | NIATCO TRUCKING CORP | | | SCAC3 |
| 13 | NIAG | Niederrheinische Verkehrsbetriebe AG | Moers | D | privat-bahn.de |
| 14 | NIAG | Niederrheinische Verkehrsbetriebe AG | | D | TRAFFIC |
| 15 | NIAG | Niederrheinische Verkehrsbetriebe | | DE | VKM |
| 16 | NIAJ | Consolidated Rail Corp. | 1/1980 | | NAKINA |
| 17 | NIAJ | Niagara Junction Ry. Co. | 1/1975 | | NAKINA |
| 18 | NIAJ | Niagara Junction Ry. Co. | Jan-75 | | NRHS |
| 19 | NIAJ | Consolidated Rail Corp. | Jan-80 | | NRHS |
| 20 | NIAJ | CONRAIL [NIAGARA JUNCTION RAILWAY] | | | PWRC |
| 21 | NIAJ | Niagara Junction Railway (Conrail) | | | RSRV |
| 22 | NIAL | NIAGARA LEASING CORP | | | SCAC3 |
| 23 | NIAR | NICHOLS & RONK INC | | | SCAC3 |
| 24 | NIAT | NATIONAL TRANSPORT SERVICES CO INC | | | SCAC3 |
| 25 | NIAT | NIAGARA TANK LINES INC | | | SCAC4 |
| 26 | NIAX | Niagara & Western New York R.R. Co., Inc. | 7/2005 (not listed) | | NAKINA |
| 27 | NIAX | Niacet Chemicals Division, United States Vanadium Corp. | 1/1946-1/1950 | | NAKINA |
| 28 | NIAX | Niacet Chemicals Corp. | 7/1930-1/1945 | | NAKINA |
| 29 | NIAX | *NIACET CHEMICALS DIV., US VANADIUM CORP. | | | PWRC |
| 30 | NIAX | *NIAGARA & WESTERN NEW YORK RAILROAD | | | PWRC |
| 31 | NIAX | Niagara and Western New York Railroad | | | RSRV |
| 32 | NIAX | Niagara & Western New York Railroad | | USA | TRAFFIC |
| 33 | NIBC | NIBCO DE REYNOSA SA DE CV | | | SCAC4 |
| 34 | NIC | Northern Illinois Commuter | Callsign: Illinois Commuter, | USA | AVCODES |
| 35 | NIC | Northern Illinois Commuter | | | ICAO1 |
| 36 | NICA | NICHOLS CAMBRIDGE EXPRESS | | | SCAC3 |
| 37 | NICC | NICHOLS TRUCKING | | | SCAC3 |
| 38 | NICD | Northern-Indiana Commuter Transportation District | 1/1994-7/2005 | | NAKINA |
| 39 | NICD | Northern-Indiana Commuter Transportation District | 1/94-7/2000 | | NRHS |
| 40 | NICD | NORTHERN INDIANA COMMUTER TRANSPORTATION DISTRICT | | | PWRC |
| 41 | NICD | South Shore Line (NICTD) | | | RSRV |
| 42 | NICD | NORTHERN-INDIANA COMMUTER TRANSPORT | | | SCAC3 |
| 43 | NICD | NORTHERN INDIANA COMMUTER TRANSPORT | | | SCAC4 |
| 44 | NICD | Northern Indiana Commuter Transportation District | City: Chicago | USA | TRAFFIC |
| 45 | NICE | NITRO | | | SCAC4 |
| 46 | NICE | | Real: TN, City: Nice | F | TRAFFIC |
| 47 | NICEB | Nassau Inter-County Express | Real: NICE | USA | TRAFFIC |
| 48 | NICF | NICKELS FARM | | | SCAC3 |
| 49 | NICG | NICKS CARTAGE CO | | | SCAC3 |
| 50 | NICG | NICU PRO TRUCKING INC | | | SCAC4 |
| 51 | NICH | NICHOLAS TRANSPORTATION COMPANY | | | SCAC3 |
| 52 | NICI | NOEL ICE COMPANY INC | | | SCAC3 |
| 53 | NICI | NINE ZERO FOUR SEVEN-ZERO EIGHT FOU | | | SCAC4 |
| 54 | NICJ | NICHOLAS, G L TRUCKING INC | | | SCAC3 |
| 55 | NICK | NICKS TRANSPORT LLC | | | SCAC4 |
| 56 | NICL | NICE FUEL CO LLC | | | SCAC4 |
| 57 | NICM | NICHOLSON MOBILE HOME | | | SCAC3 |
| 58 | NICN | NICOLES TRANSPORTATION | | | SCAC3 |
| 59 | NICN | NINE ZERO ONE SEVEN-ONE NINE ZERO O | | | SCAC4 |
| 60 | NICO | NICO SHIPPING CORP | | | SCAC4 |
| 61 | NICQ | NICKELS TRUCKING CO | | | SCAC3 |
| 62 | NICQ | N I C INDUSTRIES INC | | | SCAC4 |
| 63 | NICR | NICHOLAS TRANSPORT INC | | | SCAC4 |
| 64 | NICS | NICOS EXPRESS INC | | | SCAC4 |
| 65 | NICU | NIC LEASING INC | | | PWRC |
| 66 | NICU | NIC Leasing | | | RSRV |
| 67 | NICU | NIC LEASING | | | SCAC3 |
| 68 | NICV | NIC TRAVEL | | | SCAC3 |
| 69 | NICV | NICOLET TRANSPORTATION SERVICE LLC | | | SCAC4 |
| 70 | NICX | Niagara & Western New York R.R. Co., Inc. | 7/2005 (not listed) | | NAKINA |
| 71 | NICX | *NIAGARA & WESTERN NEW YORK RAILROAD | | | PWRC |
| 72 | NICX | *NILES CANYON RAILWAY | | | PWRC |
| 73 | NICX | Niles Canyon Railway | | | RSRV |
| 74 | NICZ | NORTHWEST IOWA COOP | | | PWRC |
| 75 | NID | Aeroni, S.A. de C.V. | Callsign: Aeroni, | MEX | AVCODES |
| 76 | NID | Aeroni | | | ICAO1 |
| 77 | NIDA | NORTH IDAHO SHUTTLE SERVICE INC | | | SCAC3 |
| 78 | NIDA | Kleinbahn Niebüll-Dagebüll | | D | TRAFFIC |
| 79 | NIDE | NICHOLSON, DALE E | | | SCAC3 |
| 80 | NIDF | NIEDFELDT TRUCKING SERVICE INC | | | SCAC3 |
| 81 | NIDH | NORTH IDAHO FREIGHT | | | SCAC3 |
| 82 | NIDI | NICHOLS, DON INC | | | SCAC3 |
| 83 | NIDM | NISSIN INTERNATIONAL DE MEXICO S A | | | SCAC4 |
| 84 | NIDS | NATIONAL INSTRUMENT DISTRIBUTORS IN | | | SCAC3 |
| 85 | NIDT | NIELSEN, D TRUCKING | | | SCAC3 |
| 86 | NIDU | HAPAG LLOYD A.G | | D | BIC |
| 87 | NIDU | NILE DUTCH AFRICA LINE | | | SCAC4 |
| 88 | NIE | Aeroejecutiva Nieto, S.A. de C.V. | Callsign: Aeronieto, | MEX | AVCODES |
| 89 | NIE | Aeroejecutiva Nieto | | | ICAO1 |
| 90 | NIEC | NIERMANN CARTAGE COMPANY | | | SCAC3 |
| 91 | NIED | NIEDERGERKE TRUCK LINE, INCORPORATE | | | SCAC3 |
| 92 | NIEE | NIEMIEC EXPRESS | | | SCAC3 |
| 93 | NIEE | NIEB, E SERVICES INCORPORATED | | | SCAC4 |
| 94 | NIEG | NIELSEN SHIPPING LTD. | | | SCAC3 |
| 95 | NIEG | NINE ONE FOUR SEVEN-EIGHT ZERO FIVE | | | SCAC4 |
| 96 | NIEJ | NIELSEN, JIM DELIVERY LTD | | | SCAC3 |
| 97 | NIEL | NIELSEN OIL CO INC | | | SCAC4 |
| 98 | NIEN | NIENEIER BROS INC | | | SCAC3 |
| 99 | NIEO | NIETO AND SONS TRUCKING, INC | | | SCAC3 |
| 100 | NIEP | NATIONAL INDUSTRIES EMBROIDERY PLUS | | | SCAC4 |
