United States 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

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