Proofreading and Editing Precision Practice Exam

ZIP code lookups rely on the official source that assigns and maintains the codes: the United States Postal Service. The USPS hosts the ZIP Code Lookup tool on usps.com, which provides authoritative, up-to-date ZIP codes for given addresses and confirms proper routing for mail. That official site is the most reliable and widely used reference for ZIP codes because it directly manages the coding system.

The other sites listed are not the official repository for ZIP codes. A private courier site may offer address services, but it doesn’t control or guarantee ZIP code data. Third-party directories can be outdated or incomplete, so they aren’t as dependable for accurate ZIP code lookups.