National Model Railroad Association
The National Model Railroad Association is an American 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 was based in Chattanooga, Tennessee next to the Tennessee [Valley Railroad Museum] from 1982 to 2013 and has since relocated to Soddy Daisy.
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, for model railroad equipment in North America. Many standards defined by the NMRA are widely followed by the industry and modellers, including their H0 scale track and wheel standards and related RPs and their Digital Command Control standard set.The RP25 wheel design in particular has been critical in ensuring the reliability and interoperability of US-prototype model railroad equipment, since practically every manufacturer of such equipment uses wheels conforming to the RP. This is in marked contrast to the British market, in which there is no accepted standard among manufacturers.
In Europe, the Normen Europäischer Modellbahnen has the same role, and although there is fairly close cooperation between the two organisations the standards differ in some aspects. At times this results in some models not working as intended on layouts that mix European and American rolling stock and trackwork.