The following are reporting marks assigned by the Association of American Railroads (AAR) to rail carriers operating in North America and the companies (railroads and rail equipment owners/operators) to which they were assigned. Where multiple railroads are listed on a reporting mark, their order indicates the order of the mark's assignment; the succession is usually through mergers or buyouts.

Reporting mark standard practices

An AAR reporting mark is a sequence of two to four letters that uniquely identifies the owner of a piece of railroad rolling stock. The ampersand symbol (&) is not considered part of the reporting mark. In general, the reporting mark is derived from the assigned company's initials.

Marks that end in X are assigned to rail car owners that are not common carrier railroads themselves (typically these are private car owners, leasing companies or railroad museums). Marks that end in Z are assigned to trailer owners/operators for use on equipment that does not have flanged wheels but that will be used on North American railroads in intermodal service. Marks that end in U are assigned to container owners/operators for use on equipment that will be used in intermodal service. Marks that end in any other letter are assigned to railroads for use on railroad equipment in interchange service.

External links

• Association of American Railroads
• Establishing and Expiring a Reporting Mark (Railinc)
• Trailer, Chassis and Private Marks (Railinc)

The list

Due to this list's size, it has been split into subpages based on the first letter of the reporting mark.