mail slots or attached wall-mounted mailboxes. This development caused a substantial increase in distances walked by the mail carrier, slowing mail delivery while increasing labor costs. In order to reduce delivery times and increase efficiency, the Post Office began requiring all new suburban developments to install curbside mailboxes in place of door-to-door delivery, allowing mail carriers to remain in the vehicle while delivering the mail. In 1978, the USPS (successor to the Post Office) declared that every new development must have either curbside delivery or centralized mail delivery. Joroleman mailbox In 1915, the Joroleman mailbox, named after its designer, Post Office employee Roy J. Joroleman, was approved by the U.S. Post Office. Joroleman, who held a degree in mechanical engineering, designed his mailbox with an unusual dome-rectangular shape, incorporating a curved, tunnel-shaped roof, latching door, and rotating semaphore flag. The Joroleman mailbox has been praised as a manifestation of American functionalist industrial design. Constructed of light-gauge painted sheet steel, Joroleman designed his mailbox with an arched, tunnel-shape roof, which prevented excessive accumulation of rainwater or snow while resisting deformation. The tunnel top also simplified the process of mass production by eliminating the need for precise sheet metal bends. Stamped and formed metal straps riveted to the arched opening and the mailbox door served as a door latching mechanism, while a rotating red semaphore flag mounted on a shaft attached to the side of the mailbox served to signal the approaching mailman if there was outgoing mail inside. Fitted with a crimped or braze-on rear steel panel and a false floor to keep its contents dry in inclement or humid weather, the Joroleman mailbox required only two rivets, three axle bolts, and four screws and nuts for completion. Durable and inexpensive, the popularity of the Joroleman mailbox was further enhanced by a decision not to patent the design, but to make its specifications known to all potential manufacturers for competitive sale. Adopted across the United States, it has remained the top-selling mailbox since its introduction, and was also widely used in Canada prior to that country's decision to eliminate individual curbside delivery to rural residents. The Joroleman mailbox was originally approved for manufacture in one size, the No. 1, which could accommodate letter mail, periodicals, newspapers, catalogs, and small parcels. After July 1, 1916, the Joroleman mailbox would be the only design approved by the Post Office for new curbside mailbox