specification: API Commons Examples
specificationVersion: '0.1'
provider: Appalachian Regional Commission
providerId: appalachian-regional-commission
generated: '2026-09-07'
method: probed
source: Every request below was executed anonymously against ARC's live hosts on 2026-09-07.
description: >-
  Working, copy-pasteable calls against both ARC surfaces, with the response fact each one returned.
  ARC publishes no examples of its own, so these were produced by calling the APIs.
examples:
  - name: Read the whole contract
    operationId: getRestIndex
    request: GET https://www.arc.gov/wp-json/
    status: 200
    observed: 596,677 bytes; 371 routes across 16 namespaces, with per-argument schemas.
    note: The self-describing route index. Start here rather than assuming a path.
  - name: Count the Appalachian counties
    operationId: queryFeatureLayer
    request: >-
      GET https://services.arcgis.com/nkunl3y8FDxPkXDl/arcgis/rest/services/arc_counties/FeatureServer/0/query?where=1%3D1&returnCountOnly=true&f=json
    status: 200
    response: '{"count":423}'
    note: The statutory definition of Appalachia, as a number.
  - name: The 13 Appalachian states
    operationId: queryFeatureLayer
    request: >-
      GET https://services.arcgis.com/nkunl3y8FDxPkXDl/arcgis/rest/services/arc_counties/FeatureServer/0/query?where=1%3D1&outFields=STATE&returnDistinctValues=true&returnGeometry=false&f=json
    status: 200
    observed: >-
      Alabama, Georgia, Kentucky, Maryland, Mississippi, New York, North Carolina, Ohio,
      Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia.
  - name: County boundaries as GeoJSON
    operationId: queryFeatureLayer
    request: >-
      GET https://services.arcgis.com/nkunl3y8FDxPkXDl/arcgis/rest/services/arc_counties/FeatureServer/0/query?where=1%3D1&outFields=*&f=geojson
    status: 200
    observed: RFC 7946 FeatureCollection, 423 features, 4.85 MB, no exceededTransferLimit — one request suffices.
  - name: Read a layer's schema before querying it
    operationId: getFeatureLayer
    request: >-
      GET https://services.arcgis.com/nkunl3y8FDxPkXDl/arcgis/rest/services/arc_county_economic_status_fy2027_tiger/FeatureServer/0?f=json
    status: 200
    observed: >-
      Layer "County Economic Status, FY 2027 (regional)", polygon geometry, fields FIPS, STATE,
      COUNTY, ARC plus year-suffixed measures CLF2022-2024, EMP2022-2024, UNRATE2022-2024, TPI2024,
      PCI2024, PCMI2024, PCIUS2024, INVPCMIUS2024 and three-year variants.
  - name: List the geospatial catalog
    operationId: listFeatureServices
    request: GET https://services.arcgis.com/nkunl3y8FDxPkXDl/arcgis/rest/services?f=json
    status: 200
    observed: currentVersion 12; 108 FeatureServer entries.
  - name: Filter reports by research topic
    operationId: getReport
    request: >-
      GET https://www.arc.gov/wp-json/wp/v2/report?research_report_eval_topic=197&per_page=2&_fields=id,title,link,date
    status: 200
    observed: >-
      X-WP-Total 53, X-WP-TotalPages 27 — matching term 197 (Socioeconomic Analysis) own count, which
      is how you confirm you resolved the right vocabulary.
  - name: Resolve a taxonomy term before filtering
    operationId: getResearchReportEvalTopic
    request: GET https://www.arc.gov/wp-json/wp/v2/research_report_eval_topic?per_page=100&_fields=id,name,slug,count
    status: 200
    observed: >-
      19 terms with counts — Socioeconomic Analysis 197/53, Business and Entrepreneurship 207/31,
      Transportation 195/30, Infrastructure 213/26, Energy 194/21, Public Health 199/21.
  - name: Search everything at once
    operationId: getSearch
    request: GET https://www.arc.gov/wp-json/wp/v2/search?search=grant&per_page=1
    status: 200
    observed: X-WP-Total 243; first hit "Grant Compliance Guide" (type resource).
  - name: Pagination signals
    operationId: getReport
    request: GET https://www.arc.gov/wp-json/wp/v2/report?per_page=2&page=2
    status: 200
    observed: >-
      X-WP-Total 304, X-WP-TotalPages 152, and a Link header carrying rel="prev" and rel="next".
      cache-control public, max-age=86400.
  - name: Discover the content model
    operationId: getTypes
    request: GET https://www.arc.gov/wp-json/wp/v2/types
    status: 200
    observed: >-
      Custom types map, success_story, resource, staff, report, event, investment_priority, ldd, each
      with the taxonomies attached to it.
negative_examples:
  - name: Author identity is not public
    request: GET https://www.arc.gov/wp-json/wp/v2/users
    status: 401
    response: '{"code":"rest_user_cannot_view","message":"Sorry, you are not allowed to list users.","data":{"status":401}}'
  - name: Comments are switched off site-wide
    request: GET https://www.arc.gov/wp-json/wp/v2/comments
    status: 403
    response: '{"code":"rest_comment_disabled","message":"Comments are disabled.","data":{"status":403}}'
  - name: ArcGIS returns errors on HTTP 200
    request: >-
      GET https://services.arcgis.com/nkunl3y8FDxPkXDl/arcgis/rest/services/arc_counties/FeatureServer/99?f=json
    status: 200
    response: '{"error":{"code":400,"message":"","details":["The requested layer (layerId: 99) was not found."]}}'
    note: The single most important gotcha on this surface. Never branch on response.ok.
  - name: No OGC API - Features
    request: >-
      GET https://services.arcgis.com/nkunl3y8FDxPkXDl/arcgis/rest/services/arc_counties/OGCFeatureServer/conformance?f=json
    status: 200
    response: '{"error":{"code":400,"message":"Invalid URL","details":["Invalid URL"]}}'
  - name: The Data Report Tool is not machine-reachable
    request: GET https://data.arc.gov/data
    status: 403
    note: >-
      Cloudflare managed challenge (cf-mitigated: challenge). Returns the interstitial to every
      non-browser client.
maintainers:
  - FN: Kin Lane
    email: info@apievangelist.com