During the period of the Republic, transporta tion of many kinds of cargo took place along the post roads. Postal service became a state monopoly (1799, Post Act 1807) only after the federation of the seven sovereign provinces had been replaced by a unitary state. The introduction of railway systems limited postal ser vices to mainly letters and small parcels. The new Act of 1850 regu lated the postal services; stamps were introduced in 1852 and became obligatory in 1870. In 1928, the responsible state company, which also included telegraph and telephone services, was called Staats bedrijf der Posterijen, Telegrafie en Telefonie (PTT). This company was denationalized in 1989 as Koninklijke PTT Nederland (Royal KPN). In 1998, postal activities were transferred to the independent company TPG Post (headquartered in The Hague), which is called TNT (originally the Australian Thomas Nationwide Transport) since 2006. TNT has about 20,000 mailboxes in the Netherlands.
Historical Dictionary of the Netherlands. EdwART. 2012.