Flats Sequencing System
Flats Sequencing System (FSS) is an automated system used by the US Postal Service. It uses a dual pass sort technique to sort flats all the way to delivery sequence order. Prior to the deployment of FSS machines, flats were machine sorted to the route level only. Carriers had to manually sort all the flats they were to deliver into proper delivery order before they could embark on their routes. With FSS, when the carrier receives them they are ready to be delivered without need for any further manual sorting. FSS machines are manufactured by Northrop Grumman. Deployment began in 2008. External links 
 Promotional video done in the style of a movie trailer

Mail sorting
United States Postal Service