Using the Free Census Geocoder Programmatically (2026 Guide)

How the /geographies endpoint works, what layers come back in one call, rate limits, and the pitfalls (vintage names, PO Boxes, DNS).

One call, many layers

A single /geographies/onelineaddress call returns state, county, tract, block, congressional district, state legislative districts (upper & lower), place, urban area and combined statistical area — plus matched coordinates.

Pitfalls we hit (so you don't)

• Vintage names: Census2020_Census2021 is rejected; use Public_AR_Current + Current_Current.
• The newer host geocoding.services.geo.census.gov has flaky DNS on some resolvers; geocoding.geo.census.gov is reliable.
• Layer keys change by congress/vintage (e.g. "120th Congressional Districts") — match by pattern, not exact string.

Try it free

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

FAQ

Is Census geocoding data public domain?

Yes — U.S. federal government work, free to use commercially without attribution.