AAR Reporting Marks

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This page was last updated on March 31, 2023.

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An AAR (Association of American Railroads) reporting mark is two to four letters, and a number from 1 to 999999 that uniquely identifies the owner of a piece of railroad equipment. This includes freight cars and passenger cars, as well as non-revenue equipment used by railroads. The reporting mark is generally derived from the assigned company's initials. All rail cars in interchange service from one railroad to another must be labeled with a reporting mark. A single railroad may have numerous reporting marks due to a history of mergers and acquisitions.

Marks other than X, U or Z are assigned to common carrier railroads for use on railroad equipment in interchange service.

Marks that end in X are assigned to non-common carrier rail car owners. These include private car owners, leasing companies, and railroad museums.

Marks that end in U are assigned to owners of intermodal shipping containers.

Marks that end in Z are assigned to owners of intermodal trailers and trailer chassis.

AAR Reporting Marks at Wikipedia

Applying For A Reporting Mark

AAR no longer administers the reporting mark database. The administration is now in the hands of RaiLinc, along with the administration of UMLER (Universal Machine Language Equipment Register) equipment management and reporting system.

The AAR/RaiLinc "Request For Railroad Reporting Marks" application shows that as of 2020, there is a $525.00 admistrative fee to have a reporting mark issued.

Contact RaiLinc customer support at 1-800-544-7245.

(Read the Wikipedia article about RaiLinc; includes a link to the official RaiLinc web site)