Just the ZIP
If you know the street name, city and state and need only the ZIP code to complete the address, the U.S. Postal Service makes finding it simple. On the USPS website, type in the information you know and click the Find button. The search application returns the correct ZIP code for the address. This tool also offers users a list of cities by ZIP code. You enter the ZIP code in a search box, select Find and the application returns the names of cities within that code area.
If you don't want to use the USPS website, type the street address, city and state into the Google search box and add the words ZIP code after or before the entry. If the address is legitimate, Google usually displays a listing of residences and businesses located at or near the address with the ZIP code included.
City, State -- No Street Address
In situations where a partial address is known, such as the city and state with no street address, one of the major Internet search engines may complete it for you. Type the information you know into the box provided and hit the Search button, which sometimes looks like a magnifying glass. Scroll through the results to see if you recognize any information. Often, the results include a link to another website that may have the information. Many of these sites provide street addresses free. Some try to sell site visitors the phone numbers and background information they seek.
No Internet Access
For people who don't use the Internet, a trip or phone call to the local post office may be in order. Typically, USPS clerks look up ZIP codes for customers who ask at the counter. Some post offices also provide a large book for customers to locate the ZIP code for a particular city. In large cities that use multiple ZIP codes, the street name is required to find the correct code.