Page "Letter box" Paragraph 50

In 1978, steady increases in postal service costs caused the USPS to insist on either curbside or centralized mail delivery for new suburban neighborhoods and developments.

A 1995 cost delivery study published in a USPS Operations handbook listed per-address annual delivery costs as: Door-to-door, $ 243 ; Curbside, $ 154 ; Cluster Box ( centralized mail delivery ), $ 106.