Machine Shops
3490--Machine Shop

Machinery Manufacturing
3511--Turbines and Turbine Generator Sets
3519--Internal Combustion Engines--NEC
3531--Construction Machinery
3532--Mining Machinery
3533--Oil and Gas Field Machinery
3535--Conveyors and Conveying Equipment
3536--Hoists, Cranes and Monorails
3537--Industrial Trucks and Tractors
3541--Machine Tools, Metal Cutting Types
3542--Machine Tools, Metal Forming Types
3543--Industrial Patterns
3544--Special Dies, Tools, Jigs and Fixtures
3545--Machine Tool Accessories
3546--Power-Driven Handballs
3547--Rolling Mill Machinery
3548--Welding Apparatus
3549--Metalworking Machinery--NEC
3552--Textile Machinery
3553--Woodworking Machinery
3554--Paper Industries Machinery
3555--Printing Trades Machinery
3556--Food Products Machinery
3559--Special Industry Machinery--NEC
3561--Pumps and Pumping Equipment
3562--Ball and Roller Bearings
3563--Air and Gas Compressors
3564--Blowers and Fans
3565--Packaging Machinery
3566--Speed Changer, Drives, and Gears
3567--Industrial Furnaces and Ovens
3568--Power Transmissions Equipment--NEC
3569--General Industrial Machinery--NEC

Magazine Publishers
2721--Periodicals
2731--Book Publishing
2741--Miscellaneous Publishing

Manufacturers And Trade Association Agents
6221--Brokers--Commodity Contract

Marinas
4493--Marinas, Boat Yards, Storage and Incidental Repair and Yacht Basins
4499--Boat Cleaning or Boat Hiring, Livery, or Rental--Except Pleasure
7997--Yacht and Boating Clubs, Membership

Marine Railways
4493--Marinas, Boat Yards, Storage and Incidental Repair and Yacht Basins

Marine Service Stations
4493--Marinas, Boat Yards, Storage and Incidental Repair and Yacht Basins

Masonry Contractors
1741--Masonry and Other Stonework

Mattress And Boxsprings Manufacturing
2515--Mattress and Bedsprings

Meat Markets
5421--Meat Markets

Meat Packers
2011--Meat Packing Plants

Meat Storage
4221--Farm Product Warehouse and Storage
4222--Cold Storage Plant and Frozen Food Locker

Meat, Wholesale
5142--Meats, Frozen, Packaged
5147--Meats, Fresh, Cured or Smoked

Medical Laboratories
8071--Medical Laboratories

Medical Schools
8221--Colleges and Universities

Men's Furnishing Stores
5611--Men's Wearing Apparel

Mercantile Stores
5311--Department Stores
5331--Variety Stores
5531--Auto and Home Supply Stores
5999--Miscellaneous Retail Stores

Mercantile Rental Property

6512--Nonresidential Building Operators
6519--Real Property Lessors--NEC

Metal Processors
3312--Blast Furnaces and Steel Mills
3313--Electometallugical Products
3321--Gray and Ductile Iron Foundries
3322--Malleable Iron Foundries
3324--Steel Investment Foundries
3325--Steel Foundries--NEC
3331--Primary Copper
3334--Primary Aluminum
3339--Primary Nonferrous Metals--NEC
3341--Secondary Nonferrous Metals

Military Schools
8211--Military--Elementary and Secondary Schools
8221--Colleges and Universities

Milk Dealers
5143--Dairy Products, excluding Dried or Canned

Milk Processors
2021--Creamery--Butter
2022--Cheese--Natural and Processed
2023--Milk--Dried, Condensed, Evaporated Products
2024--Milk--Ice Cream, Frozen Products and Desserts
2026--Milk--Liquid Products Mfg.

Milliners
5632--Millinery Stores

Millwork Manufacturing
2431--Millwork

Millwrights
1796--Millwright

Mining
1011--Ion Ores
1021--Copper Ores
1031--Lead and Zinc Ores
1041--Gold Ores
1044--Silver Ores
1061--Ferroalloy Ores, Except Vanadium
1081--Metal Mining Services
1094--Uranium-Radium-Vanadium Ores
1099--Metal Ores--NEC
1221--Bituminous Coal and Lignite--Surface
1222--Bituminous Coal--Underground
1231--Anthracite Mining
1241--Coal Mining Services
1411--Dimension Stone
1422--Crushed and Broken Limestone
1423--Crushed and Broken Granite
1429--Crushed and Broken Stone--NEC
1442--Construction Sand and Gravel
1446--Industrial Sand
1455--Kaolin and Ball Clay
1459--Clay and Related Minerals--NEC
1474--Potash, Soda, and Borate Minerals
1475--Phosphate Rock
1479--Chemical and Fertilizer Mining--NEC
1481--Nonmetallic Minerals Services
1499--Miscellaneous Nonmetallic Minerals

Miscellaneous Manufacturing--NOC
3993--Signs and Advertising Specialties
3996--Hard Surface Floor Coverings--NEC
3999--Manufacturing Industries--NEC

Miscellaneous Paper Products Manufacturing
2671--Paper Coated and Laminated, Packaging
2672--Paper Coated and Laminated--NEC
2674--Bags: Uncoated Paper and Multiwall
2675--Die-Cut Paper and Board
2676--Sanitary Paper Products
2677--Envelopes
2678--Stationery Products

Mobile Home Parks Or Courts (Lodging Places)

Mobile Home Parks Or Courts (Real Estate and Rental Properties)
6515--Mobile Home Site Operators

Money Exchanges
6099--Foreign Currency Exchanges

Monotypers
2791--Typesetting
2796--Platemaking Services
7336--Commercial Art and Graphic Design

Monument Manufacturing
3281--Cut Stone and Stone Products

Mortgage Bankers
6162--Mortgage Bankers and Correspondents
6163--Loan Brokers

Mortgage Companies
6162--Mortgage Bankers and Brokers
6163--Mortgage Brokers--using Money of Others
6211--Mortgage Buying and Selling--Rediscounting

Mortgage Servicing Agents
6162--Mortgage Bankers and Correspondents
6163--Loan Brokers

Mortuaries
7261--Morticians

Motels
7011--Hotels and Motels

Motion Picture Distributors
7822--Motion Picture Distribution Exclusive of Production

Motor Inns
7011--Hotels and Motels

Motorcycle Dealers
5571--Motorcycle Dealers

Multigraphing Shops
7336--Commercial Art and Graphic Design

Municipalities
9111--Executive Offices
9121--Legislative Bodies
9131--Executive and Legislative, Combined
9199--General Government--NEC

Music Dealers
5736--Musical Instruments Stores
5932--Musical Instruments Stores--Secondhand

Museums
8412--Museums

Music Schools
8299--Music School

Musical Instruments Manufacturing
3931--Musical Instrument

Mutual Fund Sales Representatives
6211--Mutual Fund Agents