Before HO scale became the standard for model railroading, O scale was the dominant size, with a ratio of 1:48. However, in the early 20th century, a growing demand for more compact model trains ...

The most popular scale in America is "HO," sometimes rendered as "H0," or 1:87, meaning the layout and rolling stock are reduced from 1 foot in life to 3.5 mm in model format.

For those who know their model trains, large scale includes S-scale, O-scale (Lionel size), G-scale (often found in garden railroads), F-scale, 7 ¼ gauge, and 7 ½ gauge models.