What County I Am In
ZIP Code Lookup

What county is my ZIP code in?

Enter any 5-digit US ZIP code to find the county, state, FIPS code, coordinates, and an interactive map — instantly and for free.

How ZIP code to county lookup works

A US ZIP code is a US Postal Service code that organizes mail delivery routes — not a legally defined geographic boundary. To answer "what county is my ZIP code in?", our tool performs three steps:

  • Resolve the ZIP to a coordinate. We look up a representative latitude/longitude for the ZIP (typically the geographic centroid of the delivery area) via the public Zippopotam.us dataset.
  • Run point-in-polygon against US Census county boundaries. The coordinate is checked against the official TIGER/Line county boundary dataset published by the US Census Bureau — the same authoritative source used by federal, state, and local government agencies.
  • Return the county + FIPS code. You get the county name, state, full 5-digit county GEOID (FIPS), and an interactive map preview in under a second.

Why ZIP code is sometimes ≠ exact county

Roughly 10% of US ZIP codes cross one or more county lines. This happens because USPS designs ZIPs around carrier routes and post office service areas, not around political boundaries. Examples:

  • ZIP 30097 (Johns Creek, GA) straddles Fulton and Gwinnett Counties.
  • ZIP 27617 (Raleigh, NC) covers parts of Wake and Durham Counties.
  • Many rural ZIPs on the edges of metropolitan areas span 2–3 counties.

For ZIPs in this situation, our tool returns the primary county — the county that contains the largest share of addresses in that ZIP. If you need 100% property-level accuracy (for taxes, court filings, or voter registration), use the address lookup instead, which geocodes the exact street address and runs point-in-polygon at the building level.

Examples — popular ZIP codes and their counties

  • ZIP 77001 → Harris County, TX (Houston) · FIPS 48201
  • ZIP 90001 → Los Angeles County, CA · FIPS 06037
  • ZIP 60601 → Cook County, IL (Chicago) · FIPS 17031
  • ZIP 10001 → New York County, NY (Manhattan) · FIPS 36061
  • ZIP 33101 → Miami-Dade County, FL · FIPS 12086
  • ZIP 75201 → Dallas County, TX · FIPS 48113
  • ZIP 30303 → Fulton County, GA (Atlanta) · FIPS 13121
  • ZIP 19103 → Philadelphia County, PA · FIPS 42101
  • ZIP 85001 → Maricopa County, AZ (Phoenix) · FIPS 04013
  • ZIP 98101 → King County, WA (Seattle) · FIPS 53033

Real-world use cases for ZIP-to-county lookup

  • Real estate — verify a listing's county for property tax estimates and school district mapping.
  • Voter registration — confirm the correct county election office before submitting your form.
  • Court filings — civil and small-claims cases must be filed in the right county.
  • Mailing & logistics — match customer ZIPs to county-level shipping zones or tax jurisdictions.
  • Government services — Medicaid, SNAP, vehicle registration, and licensing are all county-administered in most states.
  • Insurance & flood zones — county determines FEMA flood-zone designation and many insurance rates.
  • Public health — county health departments publish vaccination, restaurant inspection, and disease data.

Step-by-step: how to use the ZIP lookup

  1. Type or paste any 5-digit US ZIP code into the field above.
  2. Press Lookup or hit Enter.
  3. Read your result card — county name, state, FIPS code, lat/lon, and a map.
  4. For a different ZIP, just clear and re-enter.

Frequently asked questions

What county am I in by ZIP code?

Enter your 5-digit US ZIP code in the tool above. We convert the ZIP to a representative coordinate, run a point-in-polygon match against official US Census TIGER/Line county boundaries, and return the primary county, state, and full 5-digit FIPS code in under a second.

What county is 77001 in?

ZIP 77001 is in Harris County, Texas (Houston). FIPS 48201. Use the lookup above to confirm and to see the exact coordinates and map.

What county is 90001 in?

ZIP 90001 is in Los Angeles County, California. FIPS 06037. Most of Los Angeles's downtown and South LA neighborhoods sit in LA County.

What county is 10001 in?

ZIP 10001 is in New York County (Manhattan), New York. FIPS 36061.

What county is 33101 in?

ZIP 33101 is in Miami-Dade County, Florida. FIPS 12086.

Can one ZIP code cover multiple counties?

Yes — about 10% of US ZIPs cross county lines. ZIP codes are USPS mail-delivery routes, not legal boundaries. For property-level accuracy use the address lookup instead.

Is ZIP-to-county lookup free?

Yes. The tool is 100% free, requires no signup, and works on any modern device.

Does it work for ZIP+4?

Yes — enter the 5-digit ZIP. The +4 extension does not change the county for the vast majority of ZIPs.

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