US Zip Codes

All the criticism aside, we all owe our mailing efficiency to the USPS. Talk of zip codes. They are originated by the USPS. Actually, 'ZIP' is an abbreviation for 'Zone Improvement Plan'. Address locations are numerically represented by ZIP codes. Every figure in a ZIP code is very significant. Every ZIP code can be broken down into three parts: The national, regional or city and finally, the delivery area. The United States is divided into ten ZIP code areas, numbered 0-9. This knowledge is very vital, especially during ZIP code lookup.

The United States Post Office Services makes ZIP code lookup become very easy, be it by address, by company or by city. One only needs to enter the address, company name or city. After the first digit, which is the national code, the next two digits represent the city or major town, while the last two digits are the local post office or area of delivery. The combination of the first three digits represent the regional sorting and distribution center, called the Sectional Center Facility.

It is vital to clarify that ZIP codes are not boundaries. They are lines designed to increase mailing efficiency. They don't follow state boundaries. Actually, they cut across county as well as state boundaries. As much as they may be assigned to Geographic areas, they don't represent those regions at all. Instead, they denote groups of addresses or routes of mail delivery. Therefore, ZIP code 'areas' may overlap others or be overlapped by others. They may not even be found in specific Geographic areas. Examples are the navy codes, which start with 095. Other areas lack delivery routes, especially the undeveloped rural areas. In such areas delivery routes are very sparse. Therefore, no ZIP codes are assigned to them. Boundaries between ZIP codes in these areas are indefinite.

The USPS ZIP +4 Codes

The USPS incorporated the ZIP +4 codes in the system in 1983. They are made up of the basic five digit codes plus four more digits representing the lowest or smallest delivery segment like a street, some apartments, city blocks or personal addresses that receive much mail. Thus ZIP +4 codes are very specific in nature, but are not a requirement during ZIP code lookup. These codes are automatically calculated during the sorting and processing of mail.

Every post office box has a designated ZIP +4 code. In a ZIP code, the +4 represents the last four digits in a box number. Usually, the four digits can be a zero coming before the last three digits of the post office box number. In cases where the post office box number has less than four digits, zeros precede the box number. Because of this existing variance, ZIP +4 code is looked up separately for individual post office boxes. However, there are exceptional cases where USPS addresses lack ZIP +4 codes. In such cases, ZIP code lookup using geographical codes or validation of addresses requiring ZIP +4 codes may not work.

All having been said and done, the USPS provides the best platform for looking up of ZIP codes. For great and fast results, it is vital for people to familiarize themselves with the lookup process and what it entails.

US and Canadian ZIP Code Database - Immediate Download

To download the the US and Canadian ZIP code databases go to the Shop ZIP Code Databases page.

Locate a Post Office anywhere in the United States

To locate a post office in the United States go top the Locate Post Offices page.

Zip Code Look Up by State, City & County

The default page for this site is the ZIP code look up widget. There are 2 options to look up, if you want to find the ZIP code or ZIP codes for a particular cite just enter the city name and the 2-character state symbol separated by a comma. The second option is, if you have a ZIP code and you want to find the city name, enter the ZIP code in the second look up form on the default page, also called the home page.

US Post Office Look Up

To look up a US post office details, search the Locate Post Office page by city and state, then click one of the the results.