what are the blue boxes at the post office
Post box [15] In 1971 the United States Postal Service changed mail collection boxes to the current USPS Dark Blue with contrasting lettering.[12][15][16] The coming of the automobile also influenced U.S. mailbox design, and in the late 1930s, an extension chute or "snorkel" to drive-up curbside collection boxes was adopted.[11]
Postal Index Number The PIN Code system was introduced on 15 August 1972 by Shriram Bhikaji Velankar, an additional secretary in the Union Ministry of Communications.[2][3][4] The system was introduced to simplify the manual sorting and delivery of mail by eliminating confusion over incorrect addresses, similar place names and different languages used by the public.[5]