| 1701 | MCSA | Moscow, Camden and San Augustine Railroad | | | RSRV |
| 1702 | MCSE | MACS OYSTERS LTD | | | SCAC4 |
| 1703 | MCSG | MARK CROUSE TRUCKING INC | | | SCAC4 |
| 1704 | MCSH | MCSHEE | | | SCAC4 |
| 1705 | MCSI | MACSI LINES | | | SCAC1 |
| 1706 | MCSI | MCSHANE MOVING & STORAGE INC | | | SCAC4 |
| 1707 | MCSJ | MARINE CONTAINER SERVICES INC | | | SCAC4 |
| 1708 | MCSM | MACS MARITIME CARRIER SHIPPING GMBH | | | SCAC4 |
| 1709 | MCSN | MONTAGUE COLD STORAGE INC | | | SCAC4 |
| 1710 | MCSO | MACTAVISH & SONS TRANSPORT INC | | | SCAC4 |
| 1711 | MCSP | MAC SPORTS LTD | | | SCAC4 |
| 1712 | MCSR | MITSUBISHI CORPORATION LT INC | | | SCAC4 |
| 1713 | MCSS | MCS CARGO SYSTEMS, INC | | | SCAC1 |
| 1714 | MCST | MACGREGOR CRANE SERVICE LIMITED | | | SCAC4 |
| 1715 | MCSU | CHINA OCEAN SHIPPING COMPANY | | | PWRC |
| 1716 | MCSU | China Ocean Shipping | | | RSRV |
| 1717 | MCSU | MAERSK CONTAINER SERVICES BENELUX ( | | | SCAC4 |
| 1718 | MCSV | MASTER CRAFT SERVICES INC | | | SCAC4 |
| 1719 | MCSX | Mells Cargo Supply, Inc. | 1/1994 (not listed) | | NAKINA |
| 1720 | MCSX | Malvern Cold Storage Co. (American Refrigerator Transit Co.) | 7/1935 | | NAKINA |
| 1721 | MCSX | Mells Cargo Supply, Inc. | Jan-94 | | NRHS |
| 1722 | MCSX | MELLS CARGO SUPPLY, INC. | | | PWRC |
| 1723 | MCSZ | MEDITERRANEA | | | SCAC4 |
| 1724 | MCT | Transportacion Aerea del Mar de Cortes, S.A. de C.V. | Callsign: Trans Cortes, | MEX | AVCODES |
| 1725 | MCT | Transportacion Aerea Del Mar De Cortes | | | ICAO1 |
| 1726 | MCT | MECHEL CAMPIA TURZII SA | | RO | VKM |
| 1727 | MCTA | Minnesota Central R.R. Co. | added 4/1995; eliminated 4/1997; 7/2000-7/2005 | | NAKINA |
| 1728 | MCTA | Minnesota Central R.R. Co. | added 4/95; eliminated 4/97; 7/2000 | | NRHS |
| 1729 | MCTA | MINNESOTA CENTRAL RAILROAD CO. | | | PWRC |
| 1730 | MCTA | Minnesota Central Railroad | | | RSRV |
| 1731 | MCTB | M C TRUCKING COMPANY INC | | | SCAC4 |
| 1732 | MCTC | MUSEUM CENTER FOR TRANSPORTATION & COMMERCE RAILROAD MUSEUM (GALVESTON TX) | | | PWRC |
| 1733 | MCTC | MASTERS CITY TRANSPORT CO INC | | | SCAC4 |
| 1734 | MCTJ | MACNEIL, TERRY | | | SCAC4 |
| 1735 | MCTK | M C TRUCKING | | | SCAC4 |
| 1736 | MCTM | MCT TERMINAL & TRANSPORT INC | | | SCAC4 |
| 1737 | MCTN | MITSUBISHI CORPORATION LT USA | | | SCAC4 |
| 1738 | MCTP | M C TRANSPORTATION | | | SCAC4 |
| 1739 | MCTR | Mackinac Transportation Co. | 1/1975 | | NAKINA |
| 1740 | MCTR | Mackinac Transportation Co. | Jan-75 | | NRHS |
| 1741 | MCTR | MACKINAC TRANSPORTATION CO. | | | PWRC |
| 1742 | MCTR | MCKEE FOODS TRANSPORTATION LLC | | | SCAC4 |
| 1743 | MCTS | MACS TRANSPORT SERVICES LTD | | | SCAC4 |
| 1744 | MCTS | Milwaukee County Transit System | | USA | TRAFFIC |
| 1745 | MCTT | M C T TRANSPORT INC | | | SCAC4 |
| 1746 | MCTU | MARIANA EXPRESS LINES PTE LTD | | SGP | BIC |
| 1747 | MCTV | MCCAIN TRANSPORT INC | | | SCAC4 |
| 1748 | MCTX | Modern Continental Construction Co. Inc. | 7/2000-7/2005 (not listed) | | NAKINA |
| 1749 | MCTX | Velsicol Chemical Corp. | added 4/1977; 1/1980; eliminated 7/1982 | | NAKINA |
| 1750 | MCTX | Michigan Chemical Corp. | 7/1954-1/1975; eliminated 4/1977 | | NAKINA |
| 1751 | MCTX | Matawan Coal Tar Products Corp. | 7/1932 | | NAKINA |
| 1752 | MCTX | Michigan Chemical Corp. | 10/57-1/75 | | NRHS |
| 1753 | MCTX | Velsicol Chemical Corp. | 1/80; eliminated 7/82 | | NRHS |
| 1754 | MCTX | Modern Continental Construction Co. Inc. | Jul-00 | | NRHS |
| 1755 | MCTX | *MATAWAN COAL TAR PRODUCTS CORP. | | | PWRC |
| 1756 | MCTX | *VELSICOL CHEMICAL CORP. [MICHIGAN CHEMICAL CORP.] | | | PWRC |
| 1757 | MCTX | +MODERN CONTINENTAL CONSTRUCTION CO., INC. | | | PWRC |
| 1758 | MCTX | Modern Continental Construction | | | RSRV |
| 1759 | MCTX | MODERN CONTINENTAL CONSTRUCTION CO | | | SCAC4 |
| 1760 | MCTY | MCCORMICKS TRANSPORT SYSTEMS INC | | | SCAC4 |
| 1761 | MCTZ | MOUNTAIN CEMENT | | | PWRC |
| 1762 | MCTZ | MCT TRANSPORTATION LLC | | | SCAC4 |
| 1763 | MCU | MID COLUMBIA BUS CO INC | | | SCAC4 |
| 1764 | MCU | Mediterranea Centrale Umbra | 1915 - 1956 | I | TRAFFIC |
| 1765 | MCUC | MCCULLEY MARINE SERVICES INC | | | SCAC4 |
| 1766 | MCUH | MAYER CUSTOM HOUSE BROKER INC | | | SCAC4 |
| 1767 | MCUK | MCMASTER UNIVERSITY | | | SCAC4 |
| 1768 | MCUN | MCLAUGHLIN & CHARLES TRUCKING CORP | | | SCAC4 |
| 1769 | MCUQ | MACS TRUCKING | | | SCAC4 |
| 1770 | MCUR | METRO COURIERS INC | | | SCAC4 |
| 1771 | MCUU | MCR MOBILE CONTAINER REPAIR AB | | S | BIC |
| 1772 | MCUU | MCT | | | SCAC4 |
| 1773 | MCUX | Monroe Chemical Works (River Raisin Paper Co.) | 7/1923-7/1930 | | NAKINA |
| 1774 | MCUX | RIVER RAISEN PAPER CO. [MONROE CHEMICAL WORKS] | | | PWRC |
| 1775 | MCV | MTC Aviacion, S.A. de C.V. | Callsign: MTC Aviacion, | MEX | AVCODES |
| 1776 | MCV | MTC Aviacion | | | ICAO1 |
| 1777 | MCVA | MORENO CALVILLO, MARIA ANGELICA | | | SCAC4 |
| 1778 | MCVD | MAIL CENTER SERVICES INC | | | SCAC4 |
| 1779 | MCVH | MCH LOGISTICS LLC | | | SCAC4 |
| 1780 | MCVI | MORENO CORONADO, VIDAL | | | SCAC4 |
| 1781 | MCVQ | MILLER CONCRETE & EXCAVATION | | | SCAC4 |
| 1782 | MCVR | MAC TRANSPORT SERVICES | | | SCAC4 |
| 1783 | MCVS | MID CONTINENT VAN SERVICE INC | | | SCAC4 |
| 1784 | MCVT | L E MCVVOY TRUCKING | | | SCAC4 |
| 1785 | MCVX | The Firefighters Education and Training Foundation | 7/2005 | | NAKINA |
| 1786 | MCVX | Massachusetts Call/Volunteer Firefighters Association | 7/2000 (not listed) | | NAKINA |
| 1787 | MCVX | Massachusetts Call/Volunteer Firefighters Association | Jul-00 | | NRHS |
| 1788 | MCVX | FIREFIGHTERS EDUCATION & TRAINING FOUNDATION [MASSACHUSETTS CALL/VOLUNTEER FIREFIGHTERS ASSOCIATION] | | | PWRC |
| 1789 | MCVX | Massachusetts Call Volunteer Firefighters' Association | | | RSRV |
| 1790 | MCVX | FIREFIGHTERS EDUCATIONAL AND TRAINI | | | SCAC4 |
| 1791 | MCVY | MASTER CONVEYORS INC | | | SCAC4 |
| 1792 | MCWC | MCWILLIAMS CONSTRUCTION LIMITED | | | SCAC4 |
| 1793 | MCWE | MAC WELD MACHINING LTD | | | SCAC4 |
| 1794 | MCWG | MATTHEWS, C W CONTRACTING CO INC | | | SCAC4 |
| 1795 | MCWK | MILLER'S CUSTOM WORK, INC | | | SCAC1 |
| 1796 | MCWM | MCWILLIAMS MOVING & STORAGE | | | SCAC4 |
| 1797 | MCWN | MCW TRANSPORT (2000) INC | | | SCAC4 |
| 1798 | MCWP | MCWHERTER PETROLEUM LTD | | | SCAC4 |
| 1799 | MCWQ | MASTER CRAFT WINDOWS & DOORS | | | SCAC4 |
| 1800 | MCWR | MCWHORTER FARMS LLC | | | SCAC4 |
