United States Postal Codes and Addresses Guide

The United States uses a nationwide postal code system called the ZIP Code, run by the United States Postal Service (USPS). A ZIP code has five digits, and an optional four-digit extension (ZIP+4) narrows it down to a smaller delivery segment. An American address normally lists the recipient, a street number and name, an optional unit, the city, a two-letter state abbreviation and the ZIP code.

How the national system works

ZIP stands for Zone Improvement Plan. ZIP codes were created to help sort mail efficiently, so they describe delivery routes and sorting areas rather than neat geographic shapes. A ZIP code may cover part of a city, several towns, or a single large building or organization. Because they follow routes, ZIP codes do not always line up with city, county or even state boundaries.

Every state, the District of Columbia and the US territories use ZIP codes. Military mail overseas uses special APO, FPO and DPO addresses that still carry a ZIP code.

How addresses are written

The line order goes from the most specific item to the broadest: the person or business, the street line with the number first, then city, state and ZIP code. A typical address looks like this:

Jane Doe
123 Example Street, Apt 4B
Sampletown, ST 12345

The street number comes before the street name, and directional words such as North or West are part of the street name. See the full rules in how to write a United States address.

How UPCS codes work in the United States

UPCS (Universal Post Code System) gives any point on the map a short code. In the United States, codes start with the prefix US, followed by two blocks of letters and digits, for example US-XXXX-XXXX (a placeholder, not a real code). Each code stands for a 3 m by 3 m grid cell, and the same coordinates always give the same code.

A UPCS code is not an official postal code. It is not issued by the USPS or any government body, and it does not replace the ZIP code. It is a complement: a precise pin that can travel with an address, which is useful for a back entrance, a gate, a loading dock, or a house on a long rural road.

In this guide

This section has four more pages. Read ZIP code format explained for the structure of the five-digit and nine-digit codes. Use how to write an address for the line-by-line layout. If you are unsure of a code, see how to find a ZIP code. Shops and couriers can read about delivery and addressing challenges. You can also browse all country guides.