The smallest practical model railroading scale was also developed in Germany. Toy manufacturer Marklin released the first Z scale (1:220) model trains in 1972, assigned the last letter of the alphabet since it was assumed no smaller trains could be made! When these trains were later imported to America, they were first dismissed as a novelty. However, as manufacturing processes improved and the tiny mechanisms became more reliable, they gained their own niche following. While the selection of trains and accessories can be limited, a small number of manufacturers are dedicated to producing American-style Z scale trains.
From: Railroad Model Craftsmen Magazine December 25, 2016