2. United States ZIP Codes

United States ZIP Codes

About US ZIP Codes

ZIP codes were introduced in the US in 1963 to improve the efficiency of mail delivery. The system divides the country into numbered postal zones using a 5-digit code. The first three digits represent a specific region, while the last two digits represent a specific delivery area within that region. Some larger cities have multiple ZIP codes for different neighborhoods or districts. ZIP codes are now used for a variety of purposes beyond mail delivery, including demographic analysis and marketing research.

Types of Zip Codes:

  • Standard ZIP codes: These are the most common type of ZIP code and are used for all other delivery locations.
  • Unique ZIP codes: These are assigned to a single high-volume address, such as a large business or government agency.
  • Military ZIP codes: These are used for military bases, ships, and other military installations.
  • P.O. Box ZIP codes: These are assigned exclusively to post office boxes at a particular post office.
  • Post office box only ZIP codes: These are used exclusively for post office boxes at a particular post office.
  • ZIP+4 codes: These are 9-digit codes that provide a more specific location within the original 5-digit ZIP code.

ZIP Codes by State