| 3101 | NIMX | Naporano | | | RSRV |
| 3102 | NIMX | Naparano Iron and Metal Co. | | USA | TRAFFIC |
| 3103 | NIN | Nurman Avia Indopura | Callsign: Nurvindo, | RI | AVCODES |
| 3104 | NIN | Niger Airlines S.A. | IATA: 6N, Callsign: Niger Airlines, | RN | AVCODES |
| 3105 | NIN | Nurman Avia Indopura | | | ICAO1 |
| 3106 | NINB | NINA (BERMUDA) LTD AGOURA HILLS CA | | | SCAC4 |
| 3107 | NIND | NORRIS INDUSTRIES | | | SCAC3 |
| 3108 | NINH | NETMOVE INC | | | SCAC4 |
| 3109 | NINI | NATIONAL INDUSTRIES INC | | | SCAC3 |
| 3110 | NINJ | NAIJA MOTORS INC | | | SCAC4 |
| 3111 | NINK | NEIER INC | | | SCAC4 |
| 3112 | NINL | NOVELTY INC | | | SCAC4 |
| 3113 | NINM | NINNEMAN, A J TRUCKING | | | SCAC3 |
| 3114 | NINN | NOBLES INC | | | SCAC4 |
| 3115 | NINO | NINO SHIPPING CO., LTD. | | | SCAC3 |
| 3116 | NINO | NINE ZERO SIX ONE-ONE ONE | | | SCAC4 |
| 3117 | NINP | NATIONEX INC | | | SCAC4 |
| 3118 | NINR | NORTHSIDE INC | | | SCAC4 |
| 3119 | NINT | NINE ONE THREE FOUR-FOUR SEVEN NINE | | | SCAC4 |
| 3120 | NINU | REF TRANS 2013 LTD | | GE | BIC |
| 3121 | NINV | NCT INC | | | SCAC4 |
| 3122 | NINY | NEWMAN INDUSTRIES | | | SCAC4 |
| 3123 | NIOL | NICHELSON OIL INC | | | SCAC3 |
| 3124 | NIOL | NICHELSON OIL INC | | | SCAC4 |
| 3125 | NIOS | NIEMETH, OSCAR TOWING INC | | | SCAC3 |
| 3126 | NIOT | NICHOLSON TRANSFER & STORAGE CO INC | | | SCAC3 |
| 3127 | NIOT | NICHOLSON TRANSFER & STORAGE CO INC | | | SCAC4 |
| 3128 | NIOU | ROYAL NIOZ | | NL | BIC |
| 3129 | NIPP | NIPPON EXPRESS U S A INC | | | SCAC4 |
| 3130 | NIPP | Nippon Express Co. | | J | TRAFFIC |
| 3131 | NIPS | NORTHERN INDIANA PUBLIC SERVICE CO. | | | PWRC |
| 3132 | NIPT | NIPPERT, GARY TRUCKING INC | | | SCAC3 |
| 3133 | NIPU | NORTH INLAND PORT INTERNATIONAL EXPRESS CO.,LTD | | PRC | BIC |
| 3134 | NIPX | Northern Indiana Public Service Co. | 7/1932 | | NAKINA |
| 3135 | NIPX | NORTHERN INDIANA PUBLIC SERVICE CO. | | | PWRC |
| 3136 | NIQU | NUUK IMEQ | | GRO | BIC |
| 3137 | NIR | Norsk Flytjeneste AS | Callsign: Norseman, Founded in 1961. Merged into Wideroe in 1996. ICAO designator changed from PEN | N | AVCODES |
| 3138 | NIR | Norsk Flyrjeneste | | | ICAO1 |
| 3139 | NIR | NORTHEAST ILLINOIS RAILROAD CORP. | | | PWRC |
| 3140 | NIR | Northern Ireland Railways Company Limited | | UK | VKM |
| 3141 | NIRA | NIAGARA LOGISTICS INC | | | SCAC4 |
| 3142 | NIRC | NORTHEAST ILLINOIS REGIONAL COMMUTER RAILROAD CORP. (METRA) | | | PWRC |
| 3143 | NIRH | NICHOLS, ROBERT HAULING | | | SCAC3 |
| 3144 | NIRH | NICHOLS, ROBERT TRUCKING INC | | | SCAC4 |
| 3145 | NIRI | NIRINT SHIPPING BV | | | SCAC4 |
| 3146 | NIRO | NiRoVe GmbH | | DE | VKM |
| 3147 | NIRS | NICHOLSON AIR SERVICES | | | SCAC3 |
| 3148 | NIRU | NIRINT SHIPPING BV | | NL | BIC |
| 3149 | NIRU | NIRINT SHIPPING BV | | | SCAC4 |
| 3150 | NIRV | NIRVANA TRANSPORT INC | | | SCAC4 |
| 3151 | NIRX | General Electric Rail Services Corp. | added 1/2000; 7/2000-7/2005 | | NAKINA |
| 3152 | NIRX | General Electric Railcar Services Corp. | added 1/1984; 1/1994; eliminated 1/2000 | | NAKINA |
| 3153 | NIRX | North American Car Corp. | added 4/1962; 7/1965-1/1980; eliminated 1/1984 | | NAKINA |
| 3154 | NIRX | North American Car Corp. | added 4/62; 7/65-1/80 | | NRHS |
| 3155 | NIRX | General Electric Railcar Services Corp. | 1/94; eliminated 1/2000 | | NRHS |
| 3156 | NIRX | General Electric Rail Services Corp. | added 1/2000; 7/2000 | | NRHS |
| 3157 | NIRX | (NATX) GENERAL ELECTRIC RAIL SERVICES CORP. [NORTH AMERICAN CAR CORP.] | | | PWRC |
| 3158 | NIRX | GE Rail Services | | | RSRV |
| 3159 | NIRX | GENERAL ELECTRIC RAILCAR SERVICES C | | | SCAC4 |
| 3160 | NIS | Nicaraguenses de Aviacion S.A. (NICA) | IATA: 6Y, Callsign: Nica, Designator 6Y recalled by IATA | NIC | AVCODES |
| 3161 | NIS | Nicaraguense De Aviacion | | | ICAO1 |
| 3162 | NIS | Nishi-Nippon Railroad Co., Ltd (Nishitetsu) | | J | TRAFFIC |
| 3163 | NISB | Nishitetsu Bus | | J | TRAFFIC |
| 3164 | NISD | NISHIDA SHIPPING LTD. | | | SCAC3 |
| 3165 | NISD | NISHAN TRANSPORT INC | | | SCAC4 |
| 3166 | NISD | Nissan Diesel Motor Co. | | J | TRAFFIC |
| 3167 | NISE | NIESE TRANSPORT INC | | | SCAC4 |
| 3168 | NISEKO | Niseko Bus Co. | | J | TRAFFIC |
| 3169 | NISH | NISHO SHIPPING CO LTD | | | SCAC3 |
| 3170 | NISHIT | Nishi Tokyo Bus Co., Ltd. | | J | TRAFFIC |
| 3171 | NISI | NISI SHIPPING COMPANY LIMITED | | | SCAC3 |
| 3172 | NISN | NISSIN INTERNATIONAL TRANSPORT USA | | | SCAC3 |
| 3173 | NISN | NISSIN INTERNATIONAL TRANSPORT USA | | | SCAC4 |
| 3174 | NISP | NATIONAL SPINNING CO INC | | | SCAC3 |
| 3175 | NISQ | NISTLER TRUCK | | | SCAC3 |
| 3176 | NISR | Niigata Seaside Railway | Freight-only railway line, 1970 - 2002 | J | TRAFFIC |
| 3177 | NISS | NISSUI SHIPPING CORPORATION, TOKYO | | | SCAC3 |
| 3178 | NISS | NISSUI SHIPPING CORPORATION, TOKYO | | | SCAC4 |
| 3179 | NISSAN | | | J | TRAFFIC |
| 3180 | NISU | NORSUL INTERNACIONAL S A | | | SCAC3 |
| 3181 | NISU | TECHNOPYR SA | | | SCAC4 |
| 3182 | NISV | NATIONWIDE IMAGING SERVICES INC | | | SCAC4 |
| 3183 | NISX | North American Car Corp. | added 4/1961; 4/1961-1/1975; eliminated 10/1979 | | NAKINA |
| 3184 | NISX | North American Car Corp. | added 4/61; 4/61-1/75 | | NRHS |
| 3185 | NISX | | | | TRAFFIC |
| 3186 | NISZ | NATIONAL INDUSTRIAL SERVICES | | | PWRC |
| 3187 | NIT | Midwest Aviation Corp. | Callsign: Nighttrain, | USA | AVCODES |
| 3188 | NIT | Middle Georgia State College | Callsign: Nighttrain, | USA | AVCODES |
| 3189 | NIT | Midwest Aviation | | | ICAO1 |
| 3190 | NIT | Neuss Intermodal Terminal GmbH | Neuss | D | privat-bahn.de |
| 3191 | NITC | NO IDLE TRANSPORT | | | SCAC4 |
| 3192 | NITE | NITEOWL TRANSPORTATION | | | SCAC4 |
| 3193 | NITI | N I T INC | | | SCAC3 |
| 3194 | NITM | NIC-O-TIME INC | | | SCAC3 |
| 3195 | NITN | NITTANY OIL COMPANY | | | SCAC4 |
| 3196 | NITO | NITE OIL CO | | | SCAC4 |
| 3197 | NITP | NIGHT STAR TRANSPORT | | | SCAC4 |
| 3198 | NITQ | NEITZ, CHARLES W | | | SCAC3 |
| 3199 | NITR | NITCHER TRUCKING | | | SCAC3 |
| 3200 | NITR | NITCHER TRUCKING | | | SCAC4 |
