- Bulk Carriers: All vessels designed to carry bulk cargo such as grain, fertilizers, ore, and oil.

- Combination Passenger and Cargo Ships: Ships with a capacity for 13 or more passengers.

- Freighters:
Breakbulk vessels both refrigerated and unrefrigerated, containerships, partial containerships, rollon/rolloff vessels, and barge carriers.

- Barge Carriers: Ships designed to carry barges; some are fitted to act as full containerships and can carry a varying number of barges and containers at the same time. At present this class includes two types of vessels LASH and Sea-Bee.

- General Cargo Carriers: Breakbulk freighters, car carriers, cattle carriers, pallet carriers and timber carriers.

- Full Containerships: Ships equipped with permanent container cells, with little or no space for other types of cargo.

- Partial Containerships: Multipurpose containerships where one or more but not all compartments are fitted with permanent container cells. Remaining compartments are used for other types of cargo.

- Roll-on/Roll-off vessels: Ships specially designed to carry wheeled containers or trailers using interior ramps.

- Tankers: Ships fitted with tanks to carry liquid cargo such as: crude petroleum and petroleum products; chemicals, Liquefied gasses(LNG and LPG), wine, molasses, and similar product tankers.

Source: U.S. Maritime Administration.