What is a ZIP Code?
A ZIP code (Zone Improvement Plan code) is a postal code used by the United States Postal Service (USPS). Introduced in 1963, ZIP codes help sort and deliver mail efficiently across the country. Each ZIP code identifies a specific geographic delivery area — from a city neighborhood to a rural route. The standard ZIP code is 5 digits, with an optional 4-digit extension (ZIP+4) for more precise location.
Frequently Asked Questions
What is the difference between a ZIP code and a postal code?
ZIP code is the term used in the United States. Other countries use the term postal code for the same concept — a numeric or alphanumeric code that identifies a mail delivery area. They serve the same purpose but have different formats in different countries.
How many digits are in a US ZIP code?
A standard US ZIP code has 5 digits. There is also an extended ZIP+4 format with 9 digits (5 digits, a hyphen, then 4 more digits) that identifies a more specific location within the ZIP code area.
Can I look up a ZIP code by city name?
Yes — go to the US ZIP codes section and select your state. Each state page has a search box where you can search by city name to find all ZIP codes in that city.