American OO gauge is a unique gauge with a unique history. The British started making small models in the 1920s with a body scale of 1/76 but the track gauge of 5/8 inch. The appropriate scale for track of that width would be 1/87, so the bodies were over scale. They still make these models–they are British OO or HO/OO, which maintains this scale/gauge mismatch. [They also make models in several versions of a correct gauge with the 1/76 bodies, including EM Gauge and Scalefour, but that is another post for another day.]

When these first models came to the United States in the early 1930s two different tactics were taken to correct this mismatch. One was HO gauge, which has bodies and track correct for 1/87. The other was American OO (pronounced “double O”), which retained the slightly larger body scale of 1/76 and corrected the track gauge to 3/4 inch. The models are noticeably larger than HO but smaller than S gauge, which was developed later.

American OO was produced in large commercial quantities by Lionel and Scale-Craft, and in significant quantities by companies such as Famoco, Nason Railways, Schorr, and many other firms, primarily between 1934 and 1954. It is to the history and operation of these models today that this website is directed.

UPDATE 2013/21: This is where things began for American OO Today — the very first article on the site, the above only being slightly updated from the original text posted. This image illustrates the comparison of American and British OO (and HO) gauges, and is from the October, 1939 issue of Miniature Railroading.