The Posthorn-type stamps were designed by architect Andreas Friedrich Wilhelm von Hanno in 1871 (18 years after the first trains were running in Norway). With only slight alterations to the design and inscription, re-engraving of the die, new printing methods, etc., the original design has remained unchanged until today. It is commonly acknowledged as the world’s longest uninterrupted stamp series. The design comprises the name of the country, the Royal Crown and Posthorn (indicating official postal activity), and small wheels and wings in each corner representing speedy transportation of mail by rail [almost prophetic for air mail]. The wheels bespeak the railways as carriers of the mails.
An additional interesting railway correlation to the Posthorns is that the designer of these stamps, *architect A.F.W. von Hanno was a professional railway architect – he was the architect of the station buildings of the first Norwegian Railway (Hovedbanen) and the first state railway in Norway (Kongsvinger Railway), and together with a colleague, he designed the first railway station in Oslo. It is known also that in the same year as he created the stamp design (1871), von Hanno was working on a draft/sketch design project for the second station in Oslo, the Western Line Station.
By 2002, 153 main issues, in addition to seven stamps-on-stamps, had been issued. Numerous design differences exist in vertical shading lines, the size and shading of the posthorn, and in the corner wings of all these definitive stamps issued over the years. Norway Post has issued also much postal stationery franked with imprinted posthorn stamps as indicia.

Survey of posthorn stamps