S Scale is one of the oldest model railroading scales. The earliest known 1:64 scale train was constructed from card in 1896. The first working models appeared in England in the early 20th century. Modeling in S gauge increased in the 1930s-1940's when CD Models marketed 3/16" model train sets under the name American Flyer Trains. Later American Flyer was purchased by A.C. Gilbert Co., and the term S Gauge was adopted by the National Model Railroading Association (NMRA) in 1943 to represent that gauge that was half of #1 gauge (1/32). And as they say, the rest is history. A.C. Gilbert's improvements in 1/64 modeling and promotions of S gauge largely shaped the world of 1/64 modeling today.
The first trains marketed as S gauge appeared in the 1930s when American Flyer marketed a 1:64 scale train that ran on 3-rail track similar to that of Lionel. In 1946 following the end of World War II, A.C. Gilbert's American Flyer introduced an S-gauge train running on two-rail track for greater realism, and S gauge entered what many consider its heyday (although there is more available in S scale today than was available during this period) . However, during that period, Lionel outsold American Flyer nearly 2 to 1. American Flyer's parent company went out of business and the brand was sold to to a holding company that also owned Lionel in 1967.
Lionel re-introduced S gauge trains and accessories under the American Flyer name in 1979. Another S manufacturer, American Models, entered the marketplace in 1981 and is now also one of the major S suppliers. S-Helper Service, another major S gauge manufacturer of locomotives, rolling stock, track and other products, began operations in 1989 and delivered their first S products in 1990. And while the S scale market has seen a number of brass model manufacturers, today the major brass model supplier in S scale/S gauge is River Raisin Models. Today's S gauge/S scale modelers have a greater selection and higher quality products, from a wide range of manufacturers, that at any time in the past. In addition to the basics of locomotives, rolling stock, and track, various manufacturers now offer S scale structures, detail parts, figures, other scenic items, bridges, and more.
What's it worth? Take a look at this S Gauge price guide: sold listings for a value indication.