United States Census Bureau Geographic Services API

openapi: 3.1.0
info:
  title: Census Data American Community Survey Geographic Services API
  description: The United States Census Bureau Data API provides programmatic access to statistical data from Census Bureau surveys and datasets. The API covers demographic, economic, housing, and social data through a query-based interface. Key datasets include the American Community Survey (ACS), Decennial Census, Population Estimates, County Business Patterns, and many more. Users can query data by geographic level (national, state, county, tract, block group) and filter by hundreds of statistical variables. An API key is optional (up to 500 requests/day without one) but required for higher usage.
  version: 2.0.0
  contact:
    name: Census Developer Forum
    url: https://www.census.gov/data/developers.html
    email: cnmp.developers.list@census.gov
  x-tags:
  - Demographics
  - Federal Government
  - Open Data
  - Statistics
servers:
- url: https://api.census.gov/data
  description: Census Data API
tags:
- name: Geographic Services
  description: Geocoding and geographic boundary services
paths:
  /geocoder/locations/onelineaddress:
    get:
      operationId: geocodeOnelineAddress
      summary: Geocode One-Line Address
      description: Converts a one-line address string to geographic coordinates and census geography identifiers (state, county, tract, block FIPS codes).
      tags:
      - Geographic Services
      parameters:
      - name: address
        in: query
        required: true
        description: Full address as a single string (e.g., "4600 Silver Hill Rd, Washington DC 20233")
        schema:
          type: string
      - name: benchmark
        in: query
        required: true
        description: The geocoding benchmark to use (e.g., Public_AR_Current, Public_AR_Census2020)
        schema:
          type: string
          default: Public_AR_Current
      - name: vintage
        in: query
        required: false
        description: Geographic vintage for returned geography identifiers (e.g., Current_Current, Census2020_Census2020)
        schema:
          type: string
      - name: format
        in: query
        required: false
        description: Response format
        schema:
          type: string
          enum:
          - json
      - name: layers
        in: query
        required: false
        description: Geographic layers to include in the response
        schema:
          type: string
      responses:
        '200':
          description: Geocoding result with coordinates and census geography
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GeocodeResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
  /geocoder/locations/address:
    get:
      operationId: geocodeAddress
      summary: Geocode Structured Address
      description: Converts a structured address (street, city, state, ZIP) to geographic coordinates and census geography identifiers.
      tags:
      - Geographic Services
      parameters:
      - name: street
        in: query
        required: true
        description: Street address (e.g., "4600 Silver Hill Rd")
        schema:
          type: string
      - name: city
        in: query
        required: false
        description: City name
        schema:
          type: string
      - name: state
        in: query
        required: false
        description: Two-character state abbreviation or FIPS code
        schema:
          type: string
      - name: zip
        in: query
        required: false
        description: Five-digit ZIP code
        schema:
          type: string
      - name: benchmark
        in: query
        required: true
        description: Geocoding benchmark to use
        schema:
          type: string
          default: Public_AR_Current
      - name: vintage
        in: query
        required: false
        description: Geographic vintage for returned geography identifiers
        schema:
          type: string
      - name: format
        in: query
        required: false
        description: Response format
        schema:
          type: string
          enum:
          - json
      responses:
        '200':
          description: Geocoding result with coordinates and census geography
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GeocodeResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
components:
  schemas:
    GeocodeResponse:
      type: object
      properties:
        result:
          type: object
          properties:
            input:
              type: object
              description: The input address that was geocoded
            addressMatches:
              type: array
              description: Array of matched addresses
              items:
                $ref: '#/components/schemas/GeocodeAddressMatch'
    GeocodeCoordinates:
      type: object
      properties:
        x:
          type: number
          format: double
          description: Longitude
        y:
          type: number
          format: double
          description: Latitude
    GeocodeAddressMatch:
      type: object
      properties:
        tigerLineId:
          type: string
          description: TIGER/Line ID of the matched road segment
        side:
          type: string
          description: Side of the road (L or R)
        matchedAddress:
          type: string
          description: Standardized matched address string
        coordinates:
          $ref: '#/components/schemas/GeocodeCoordinates'
        addressComponents:
          type: object
          description: Parsed address components
  responses:
    BadRequest:
      description: Bad request — invalid parameters, missing required fields, or variable not found
      content:
        text/html:
          schema:
            type: string
externalDocs:
  description: Census Data API User Guide
  url: https://www.census.gov/data/developers/guidance/api-user-guide.html