Understanding US ZIP Code Ranges By State

US ZIP codes are organized geographically, with the first digit of the five-digit code representing a broad region of the country. ZIP codes starting with 0 cover the Northeast, including Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New Jersey, and parts of New York. Codes starting with 1 cover Delaware, Pennsylvania, Maryland, Washington DC, and parts of Virginia and New York. Codes starting with 2 cover the Southeast and Mid-Atlantic, including North Carolina, South Carolina, Georgia, Florida, and parts of Tennessee and Virginia. This first-digit pattern makes it possible to identify a ZIP code's general region at a glance, which is useful for building validation rules that reject obviously incorrect ZIP code and state combinations during data entry.

The middle of the country is covered by ZIP codes starting with 3 through 7. Codes starting with 3 cover Florida, Georgia, Alabama, Mississippi, Tennessee, and the Carolinas. Codes starting with 4 cover the Great Lakes region including Ohio, Indiana, Illinois, Michigan, Wisconsin, Kentucky, and West Virginia. Codes starting with 5 cover the central Midwest and Plains states including Iowa, Missouri, Nebraska, Kansas, Minnesota, and the Dakotas. Codes starting with 6 and 7 cover the South Central and Rocky Mountain region including Texas, Oklahoma, Arkansas, Louisiana, Colorado, and the Mountain states. Codes starting with 8 cover the Southwest including Arizona, New Mexico, Utah, Nevada, and parts of California. Codes starting with 9 cover the West Coast including California, Oregon, Washington, Alaska, and Hawaii. Each state has a specific range, and our state-specific pages make it easy to see which codes belong to each state at a glance.

Within each state, ZIP codes are further subdivided by city and delivery area. The second and third digits narrow down the region to a specific sectional center facility, and the last two digits identify the local post office or delivery zone. This hierarchical structure enables the USPS to sort and route mail with remarkable efficiency, processing over 400 million pieces of mail each day. Our address database includes over 400 ZIP codes covering all 50 states with accurate city assignments. You can browse our ZIP code directory to explore codes by state and see which cities they serve. For city-level exploration, our city address generator provides addresses with valid ZIP codes for each municipality.

For developers and testers, understanding ZIP code ranges helps in building validation logic that checks whether a ZIP code is valid for a given state. A simple range check can catch many common data entry errors, such as a Florida address using a California ZIP code. Our test address generator produces addresses where the ZIP code is always valid for the associated city and state, making it a reliable tool for testing address validation systems. Our random address generator provides the same consistency across all 50 states, ensuring that every generated address passes real-world validation checks. Mastering ZIP code ranges is a fundamental skill for any developer working with US address data, and our tools make it easy to put that knowledge into practice.