Append County (and County FIPS) to Every Address in Your CSV

Free browser tool that adds county name and 5-digit county FIPS to any list of U.S. addresses, powered by official Census Bureau data.

How it works

  1. Open GeoFlow
  2. Paste your addresses (one per line) or upload a CSV and pick the address column
  3. Click Run — each address is matched against the free U.S. Census Bureau Geocoder
  4. Download the enriched CSV

Example output

Real output from the tool:

Input addressCountyCongressionalState Senate (SLDU)Assembly (SLDL)Timezone
1600 Pennsylvania Ave NW, Washington, DC 20500District of Columbia (11001)1198 — Delegate District (at Large)Ward 2 (11002)— (DC has no lower chamber)America/New_York
350 5th Ave, New York, NY 10118New York County (36061)3612 — NY 12th DistrictState Senate 28 (36028)Assembly 75 (36075)America/New_York
1 Market St, San Francisco, CA 94105San Francisco County (06075)0611 — CA 11th DistrictState Senate 11 (06011)Assembly 17 (06017)America/Los_Angeles

Try it free

Open GeoFlow — free during beta

Data source: U.S. Census Bureau Geocoder (public domain). Timezone: tz-lookup (MIT).

FAQ

Does it work for PO Boxes?

No — the Census Geocoder does not geocode PO Boxes. Use a street address.

Is my file uploaded?

No. The page runs in your browser; only the address text is sent to the free Census Geocoder API.

What is a county FIPS code?

A 5-digit Federal Information Processing Series code (e.g. 06075 for San Francisco County) used to join county-level datasets.