National Model Railroad Association

The National Model Railroad Association (NMRA) is a non-profit organization for those involved in the hobby or business of model railroading. It was founded in the United States in 1935, and is also active in Canada, Australia, the United Kingdom, and the Netherlands. It was previously headquartered in Indianapolis, Indiana, and has been based in Chattanooga, Tennessee next to the Tennessee Valley Railroad Museum (TVRM) since 1982.

General

The classifications listed below are from the A.A.R. Individual roads may use other designations. Illustrations show a typical member of the class detailed underneath the following a class description indicates a rare or obsolete type.

Industry involvement

The best-known activity of the NMRA is the defining of standards, and advisory documents known as Recommended Practices (RP), for model railroad equipment. Many standards defined by the NMRA are widely followed by the industry and modellers, including their HO scale track and wheel standards (S-3, S-4) and related RPs (RP2, 8, 10-15, and 25) and their Digital Command Control (DCC) standard set (S-9.1, S-9.2, and RP9.1.1 through RP9.3.2).