As of early 2015, Amazon maintained fulfillment centers in 21 U.S states: Arizona, California, Delaware, Florida, Georgia, Indiana, Kansas, Kentucky, Maryland, Massachusetts, Nevada, New Hampshire, New Jersey, North Carolina, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, Washington and Wisconsin. Fulfillment centers are often located near airports.
Of the U.S states, Pennsylvania, California, Tennessee and Washington have the most fulfillment centers, with 7 centers each. Each fulfillment center is a large operation with hundreds of workers. Employee duties include unpacking and certifying goods as they arrive; storing goods and recording their locations, and retrieving goods for shipment to customers. .
Besides facilitating direct sales, Amazon fulfillment centers offer warehouse space and order processing for third-party sellers. In each distribution center, a central computer system keeps track of item locations and maps out ideal routes for "pickers" who gather items for shipment. On any given working day, a picker might walk 10 to 15 miles.
Amazon distribution centers use cutting-edge robotics for faster order processing. All in all, Amazon uses roughly 15,000 mobile Kiva robots. The robots deftly avoid obstacles while driving themselves to locations marked with coded stickers. With the aid of the Kiva robots, Amazon can store items in random racks and quickly retrieve them when needed.