The period between the first and second World Wars saw the rise of smaller model trains, starting with S scale (1:64) in the 1930s, popularized by American Flyer Trains (made by A.C. Gilbert Co.). These trains became popular because they ran on more realistic-looking two-rail track instead of the three-rail system used by competitor Lionel. While many collect vintage American Flyer trains, there are many manufacturers making S scale products today, including American Models and Pikesville Models. Selection of trains and accessories can be limited, but some hobbyists enjoy the challenge of building their own models from scratch and improvising from parts.
From: Railroad Model Craftsmen Magazine December 25, 2016