<Table> <Tr> <Td> </Td> <Td> This article possibly contains original research . Please improve it by verifying the claims made and adding inline citations . Statements consisting only of original research should be removed . (June 2017) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article possibly contains original research . Please improve it by verifying the claims made and adding inline citations . Statements consisting only of original research should be removed . (June 2017) (Learn how and when to remove this template message) </Td> </Tr> <P> ZIP Codes are a system of postal codes used by the United States Postal Service (USPS) since 1963 . The term ZIP is an acronym for Zone Improvement Plan; it was chosen to suggest that the mail travels more efficiently and quickly (zipping along) when senders use the code in the postal address . The basic format consists of five digits . An extended' ZIP + 4' code was introduced in 1983 which includes the five digits of the ZIP Code, followed by a hyphen and four additional digits that reference a more specific location . </P> <P> The term ZIP Code was originally registered as a servicemark by the U.S. Postal Service, but its registration has since expired . </P>

What is the 4 numbers after a zip code