Census Geocoder

@pipeworx/census-geocoder

The US Census Bureau's own geocoder: turns a US street address into a TIGER/Line coordinate and the full Census geography stack for that point — state, county, census tract, census block, place, congressional district, school district and CBSA, each with its GEOID.

Part of Pipeworx — an MCP gateway connecting AI agents to 1875+ live data sources. This is an independent, unofficial integration — not affiliated with, endorsed by, or published by the upstream provider.

Tools

• census_geocode_address(address | street/city/state/zip, benchmark?, vintage?) — forward geocode one address; returns coordinates plus the geography stack.
• census_reverse_geocode(latitude, longitude, benchmark?, vintage?) — every Census geography containing a coordinate.
• census_geocode_batch(addresses[], benchmark?, vintage?) — up to 100 addresses in one call; returns match status, standardized address, coordinates and state/county/tract/block FIPS per row, plus the assembled tract and block GEOIDs.

Auth

Keyless.

Data sources

• https://geocoding.geo.census.gov/geocoder/geographies/onelineaddress — one-line forward geocode.
• https://geocoding.geo.census.gov/geocoder/geographies/address — structured forward geocode.
• https://geocoding.geo.census.gov/geocoder/geographies/coordinates — reverse geocode.
• https://geocoding.geo.census.gov/geocoder/geographies/addressbatch — multipart CSV batch.

Related packs: census-tigerweb describes the geographies themselves (list every tract in a county); this pack answers "which tract is this address in". The geocodio pack is a commercial geocoder and is not a substitute when the answer has to be a Census GEOID.

Traps

• benchmark and vintage must agree. Public_AR_Current pairs with Current_Current; a mismatched pair is a 400 with an unhelpful body.
• The /geographies/* endpoints return geography; the /locations/* ones return only coordinates. This pack always uses /geographies.
• The batch endpoint is a multipart CSV POST that answers in CSV, and it geocodes every line it is handed. Send a header row and you get a No_Match result for the literal word "street". This pack never sends one.
• Batch columns are positional (id,street,city,state,zip) so an unquoted comma inside a street field shifts every later column. Each cell is quoted.
• Congressional and state-legislative layer names carry the session number, so they are matched by pattern rather than by a name that expires.

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "census-geocoder": {
      "url": "https://gateway.pipeworx.io/census-geocoder/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/census-geocoder/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — ask_pipeworx, discover_tools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

This is deliberate, not multiplexing by accident. The meta-tools are what let a scoped connection answer a question this pack does not cover — via ask_pipeworx, which routes across the whole catalog — without you adding a second MCP server. There is currently no way to mount a pack endpoint without them; if the extra schemas cost you more context than the routing is worth, connect to the full gateway once rather than to several pack endpoints.

Or connect to the full Pipeworx gateway to get every pack's tools listed directly, instead of just this one's:

{
  "mcpServers": {
    "pipeworx": {
      "url": "https://gateway.pipeworx.io/mcp"
    }
  }
}

Both URLs reach the same gateway and the same 1875+ data sources. The only difference is which pack's tools are listed directly; ask_pipeworx reaches all of them from either one.

No MCP client? Call it over HTTP

curl -X POST https://gateway.pipeworx.io/v1/tools/census_geocode_address \
  -H 'Content-Type: application/json' \
  -d '{"address":"1600 Pennsylvania Ave NW, Washington, DC 20500"}'

No account needed for the first calls. Inspect any tool: GET https://gateway.pipeworx.io/v1/tools/census_geocode_address. Find one: POST https://gateway.pipeworx.io/v1/tools/search_packs with {"query":"..."}.

Standalone (no gateway account)

This package also runs as a local stdio MCP server — no Pipeworx account, no gateway round-trip:

{
  "mcpServers": {
    "census-geocoder": {
      "command": "npx",
      "args": ["-y", "@pipeworx/mcp-census-geocoder"]
    }
  }
}

Or run it directly to confirm it starts:

npx -y @pipeworx/mcp-census-geocoder

It speaks MCP over stdin/stdout and answers initialize/tools/list/tools/call for only this pack's tools — none of the shared meta-tools the gateway connection above adds. Same source, same tools, no ask_pipeworx routing.

Using with ask_pipeworx

Instead of calling tools directly, you can ask questions in plain English — this works on the pack endpoint above as well as on the full gateway:

ask_pipeworx({ question: "your question about Census Geocoder data" })

The gateway picks the right tool and fills the arguments automatically.

More

• Docs and guides
• pipeworx.io

License

MIT