Centralized mail delivery is a unique form of mail delivery system where a letter carrier provides delivery and collection services to a number of residences from a centrally located installation – whether in a single-family subdivision or multi-family structure. Business customers also receive delivery services from a convenient central location. Centralized mail delivery equipment can be in the form of any "clustered" type mailbox – including free-standing, pedestal-mounted cluster box unit (CBU), or other cluster mailboxes mounted in a wall, kiosk, or shelter. The U.S. Postal Service prefers centralized mail delivery in all new construction because it is less expensive. The United States Postal Service aims to continue to review and modify its operations to provide universal service as efficiently and cost effectively as possible. Therefore, there is pressure to establish centralized mail delivery, which is required in some communities. History Mail delivery can be traced back to its system founder and first Postmaster, Benjamin Franklin. Since that time, the amount of new mail delivery points have steadily increased from year to year to its present estimate of 1.4 million new delivery points a year. Part of the change in mail delivery can be traced to the changes in transportation over the years. Horseback, dog sled, train, car, plane, boat, and truck have all been used to deliver the mail. As the delivery territories have grown, so, too, has the need for more efficient delivery techniques. During the nineteenth and early twentieth centuries, letter carriers knocked on the door and waited patiently for someone to answer. Efficiency experts estimated that each carrier lost an hour and a half each day just waiting for patrons to come to the door. To gain back those precious hours, in 1923 the Post Office Department mandated that every household have a mailbox or letter slot to receive mail. By the 1930, as a convenience to customers living on the margins of a city, letter carriers began delivering to customers with “suitable boxes at the curb line.” Multiple receptacles appeared, but with no regulation. In the ensuing decades American suburbanization, which exploded in the 1950s, brought an increase in curbside mailboxes. The Post Office Department first introduced curbside cluster boxes in 1967. By 2001, the US Postal Service (USPS) was approving locking mailbox designs to help customers protect their mail. Neighborhood Delivery Collection Box Units (NDCBUs) were the predecessor to today’s cluster box units. They