The Universal Postal Union (UPU), which San Marino joined in 1915, was one of the first international organisations to promote cooperation and integration among countries. Comprising 192 member states, the UPU helps to ensure a globally accessible network of products and services for all, acts in an advisory, mediating and liaison capacity and sets the rules for international exchanges. The World Post Day is celebrated every year on the 9th of October to mark the anniversary of the creation of the UPU. The design depicts on the left a carrier pigeon with a letter in its beak, on the right a white globe representing the world and the universality of the service, and at the bottom centre a post horn, against a coloured background that recalls the colours of the official logo of the anniversary.