US Census Bureau
Census Geocoding Services API

Free geocoding service that turns addresses into geographic coordinates and Census geographies (state, county, tract, block, congressional district, school district). Supports one-line address parsing, structured address parsing, address batch geocoding, coordinate reverse geocoding, and benchmark selection (current, 2020, 2010). No API key required.
Census Geocoding Services API is one of 7 APIs that US Census Bureau publishes on the APIs.io network, described by a machine-readable OpenAPI specification.
This API exposes 1 machine-runnable capability that can be deployed as REST, MCP, or Agent Skill surfaces via Naftiko.
Tagged areas include Government, Geocoding, Addresses, and GIS. The published artifact set on APIs.io includes API documentation, an OpenAPI specification, sample payloads, and 1 Naftiko capability spec.
Documentation GitHub OpenAPI
OpenAPI Specification

openapi: 3.1.0
info:
  title: Census Geocoding Services API
  description: |
    Free Census Bureau geocoder that converts addresses to coordinates and
    Census geographies. Five endpoint families exist:

    - `/locations/onelineaddress` — parse and geocode a single-line address
    - `/locations/address` — geocode a structured address (street/city/state/zip)
    - `/locations/coordinates` — reverse geocode coordinates to address
    - `/geographies/*` — same as locations but also return Census geographies
      (state, county, tract, block, congressional district, school district)
    - `/locations/addressbatch` and `/geographies/addressbatch` — submit a CSV
      of up to 10,000 addresses per request via multipart upload

    Benchmarks select the reference dataset vintage (Public_AR_Current,
    Public_AR_Census2020, Public_AR_Census2010). Vintages select the
    geographies vintage to attach when calling the `/geographies` endpoints.

    No API key required.
  version: '2026-05-25'
  contact:
    name: Census Bureau Geography Division
    url: https://geocoding.geo.census.gov/geocoder/
  license:
    name: Public Domain
    url: https://www.usa.gov/government-works
servers:
- url: https://geocoding.geo.census.gov/geocoder
  description: Census Geocoder production
tags:
- name: Locations
  description: Address to coordinates
- name: Geographies
  description: Address to coordinates plus Census geographies
- name: Batch
  description: Bulk geocoding (up to 10,000 records)
paths:
  /locations/onelineaddress:
    get:
      summary: Geocode A One-Line Address
      description: Parse a single-line address string and return matched coordinates.
      operationId: locationsOnelineAddress
      tags:
      - Locations
      parameters:
      - name: address
        in: query
        required: true
        description: Single-line street address (for example `4600 Silver Hill Rd, Washington, DC 20233`).
        schema:
          type: string
      - $ref: '#/components/parameters/BenchmarkParam'
      - $ref: '#/components/parameters/FormatParam'
      responses:
        '200':
          description: Geocoder match envelope
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/LocationsResponse'
  /locations/address:
    get:
      summary: Geocode A Structured Address
      description: Geocode using separately parsed street, city, state, and ZIP fields.
      operationId: locationsAddress
      tags:
      - Locations
      parameters:
      - name: street
        in: query
        required: true
        schema:
          type: string
      - name: city
        in: query
        required: false
        schema:
          type: string
      - name: state
        in: query
        required: false
        schema:
          type: string
      - name: zip
        in: query
        required: false
        schema:
          type: string
      - $ref: '#/components/parameters/BenchmarkParam'
      - $ref: '#/components/parameters/FormatParam'
      responses:
        '200':
          description: Geocoder match envelope
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/LocationsResponse'
  /locations/coordinates:
    get:
      summary: Reverse Geocode Coordinates
      description: Reverse geocode a latitude/longitude pair to the nearest matched address.
      operationId: locationsCoordinates
      tags:
      - Locations
      parameters:
      - name: x
        in: query
        required: true
        description: Longitude in WGS84.
        schema:
          type: number
      - name: y
        in: query
        required: true
        description: Latitude in WGS84.
        schema:
          type: number
      - $ref: '#/components/parameters/BenchmarkParam'
      - $ref: '#/components/parameters/FormatParam'
      responses:
        '200':
          description: Reverse-geocoded match envelope
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/LocationsResponse'
  /geographies/onelineaddress:
    get:
      summary: Geocode A One-Line Address With Census Geographies
      description: Like `/locations/onelineaddress` but additionally attaches the matching state, county, tract, and block per the requested vintage.
      operationId: geographiesOnelineAddress
      tags:
      - Geographies
      parameters:
      - name: address
        in: query
        required: true
        schema:
          type: string
      - $ref: '#/components/parameters/BenchmarkParam'
      - $ref: '#/components/parameters/VintageParam'
      - $ref: '#/components/parameters/FormatParam'
      responses:
        '200':
          description: Geographies match envelope
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GeographiesResponse'
  /geographies/address:
    get:
      summary: Geocode A Structured Address With Census Geographies
      description: Structured-address variant of the geographies geocoder.
      operationId: geographiesAddress
      tags:
      - Geographies
      parameters:
      - name: street
        in: query
        required: true
        schema:
          type: string
      - name: city
        in: query
        required: false
        schema:
          type: string
      - name: state
        in: query
        required: false
        schema:
          type: string
      - name: zip
        in: query
        required: false
        schema:
          type: string
      - $ref: '#/components/parameters/BenchmarkParam'
      - $ref: '#/components/parameters/VintageParam'
      - $ref: '#/components/parameters/FormatParam'
      responses:
        '200':
          description: Geographies match envelope
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GeographiesResponse'
  /geographies/coordinates:
    get:
      summary: Reverse Geocode Coordinates With Census Geographies
      description: Reverse-geocoder variant that returns Census geographies for the coordinate.
      operationId: geographiesCoordinates
      tags:
      - Geographies
      parameters:
      - name: x
        in: query
        required: true
        schema:
          type: number
      - name: y
        in: query
        required: true
        schema:
          type: number
      - $ref: '#/components/parameters/BenchmarkParam'
      - $ref: '#/components/parameters/VintageParam'
      - $ref: '#/components/parameters/FormatParam'
      responses:
        '200':
          description: Geographies match envelope
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GeographiesResponse'
  /locations/addressbatch:
    post:
      summary: Batch Geocode Addresses
      description: |
        Bulk geocode up to 10,000 addresses per request. Submit a CSV file with
        unique-id, street, city, state, ZIP columns. Returns a CSV response.
      operationId: batchLocations
      tags:
      - Batch
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              type: object
              properties:
                addressFile:
                  type: string
                  format: binary
                  description: CSV file containing up to 10,000 addresses.
                benchmark:
                  type: string
                  description: Reference dataset benchmark.
      responses:
        '200':
          description: CSV response with matched records.
          content:
            text/csv:
              schema:
                type: string
  /geographies/addressbatch:
    post:
      summary: Batch Geocode Addresses With Geographies
      description: Bulk geographies variant — same as `/locations/addressbatch` but each match is annotated with Census geographies.
      operationId: batchGeographies
      tags:
      - Batch
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              type: object
              properties:
                addressFile:
                  type: string
                  format: binary
                benchmark:
                  type: string
                vintage:
                  type: string
      responses:
        '200':
          description: CSV response with matched records and geographies.
          content:
            text/csv:
              schema:
                type: string
components:
  parameters:
    BenchmarkParam:
      name: benchmark
      in: query
      required: true
      description: Reference dataset benchmark (`Public_AR_Current`, `Public_AR_Census2020`, `Public_AR_Census2010`).
      schema:
        type: string
        examples: ['Public_AR_Current']
    VintageParam:
      name: vintage
      in: query
      required: true
      description: Geography vintage (`Current_Current`, `Census2020_Current`, `ACS2023_Current`, etc.).
      schema:
        type: string
    FormatParam:
      name: format
      in: query
      required: false
      description: Response format.
      schema:
        type: string
        enum: [json, jsonp]
        default: json
  schemas:
    LocationsResponse:
      type: object
      properties:
        result:
          type: object
          properties:
            input:
              type: object
            addressMatches:
              type: array
              items:
                $ref: '#/components/schemas/AddressMatch'
    GeographiesResponse:
      type: object
      properties:
        result:
          type: object
          properties:
            input:
              type: object
            addressMatches:
              type: array
              items:
                allOf:
                - $ref: '#/components/schemas/AddressMatch'
                - type: object
                  properties:
                    geographies:
                      type: object
                      additionalProperties:
                        type: array
                        items:
                          type: object
    AddressMatch:
      type: object
      properties:
        matchedAddress:
          type: string
        coordinates:
          type: object
          properties:
            x:
              type: number
            y:
              type: number
        tigerLine:
          type: object
          properties:
            tigerLineId:
              type: string
            side:
              type: string
        addressComponents:
          type: object
          properties:
            fromAddress:
              type: string
            toAddress:
              type: string
            preQualifier:
              type: string
            preDirection:
              type: string
            preType:
              type: string
            streetName:
              type: string
            suffixType:
              type: string
            suffixDirection:
              type: string
            suffixQualifier:
              type: string
            city:
              type: string
            state:
              type: string
            zip:
              type: string
Census Geocoding Services API

Documentation

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Examples

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OpenAPI Specification
