Originally, film posters were produced for the exclusive use by the theaters exhibiting the film the poster was created for, and were required to be returned to the distributor after the film left the theater. In the United States, film posters were usually returned to a nationwide operation called the National Screen Service (NSS) which printed and distributed most of the film posters for the studios between 1940 and 1984. As an economy measure, the NSS regularly recycled posters that were returned, sending them back out to be used again at another theater. During this time, a film could stay in circulation for several years, and so many old film posters were badly worn before being retired into storage at an NSS warehouse (most often, they were thrown away when they were no longer needed or had become too worn to be used again). Those posters which were not returned were often thrown away by the theater owner or damaged by being outside.