Apart from some other lines in North, Central and South America, 3 ft gauge was uncommon elsewhere.
3 ft (914 mm) gauge railroads were widespread in the United States in the period 1880-90.
While most of these railroads were converted to standard gauge by the start of the 20th century, a number of lines survived till the Second World War and later, and became popular subjects for modelling.
Probably the most popular prototype is the Denver and Rio Grande Western Railroad, followed by other Colorado railroads such as the Rio Grande Southern and Colorado and Southern.
Some model kits are not available new due to production having ceased but can be found on the preowned market including the Backwoods models of Irish narrow gauge locomotives and rolling stock.