Constituency boundaries

/api/public/v1/boundaries/* exposes electoral-district geometry for 342 federal ridings, ~700 provincial ridings (every province + territory except Nunavut), and ~450 municipal wards across Canada. Free-tier — boundaries are mirrored from Open North's free public API, so they ship at the same tier the upstream data is available at.

For the full per-endpoint schema with "Try it out" buttons see the Swagger UI under the Constituency boundaries tag.

Endpoints

Method	Path	Purpose
GET	/boundaries	Paginated list with level, province_territory, and bbox filters (metadata only — no GeoJSON)
GET	/boundaries/lookup	Point-in-polygon: find the riding containing a lat/lng at each level
GET	/boundaries/{source_set}/{slug}	Single boundary with simplified GeoJSON

GET /boundaries

Paginated list of constituency boundaries. Metadata only — the response does not include GeoJSON, so a page of 100 stays kilobyte-sized. Fetch geometry separately via /boundaries/{set}/{slug} when you need it.

Query parameters

Name	Type	Notes
level	federal | provincial | municipal	Filter by level.
province_territory	2-letter code	e.g. ON, AB. Federal ridings have this null — filter on level=federal instead.
bbox	minLng,minLat,maxLng,maxLat	WGS84 bounding-box filter. Uses the GIST index on the simplified geometry for fast lookup.
page	int ≥ 1	Default 1.
limit	int 1–100	Default 50.

Response

{
  "items": [
    {
      "constituency_id": "federal-electoral-districts-2023-representation-order/35079",
      "name": "Ottawa Centre",
      "level": "federal",
      "province_territory": null,
      "source_set": "federal-electoral-districts",
      "area_sqkm": 40.73,
      "centroid": { "lng": -75.7076, "lat": 45.3915 },
      "effective_from": "2023-01-01",
      "effective_to": null,
      "boundaries_version": "current"
    }
  ],
  "page": 1,
  "limit": 50,
  "total": 342,
  "pages": 7
}

Cache-Control: public, max-age=3600.

Example

curl -s -H 'Authorization: Bearer cpd_live_…' \
  'https://canadianpoliticaldata.org/api/public/v1/boundaries?level=provincial&province_territory=ON&limit=10' \
  | jq '.items[] | {name, area_sqkm, centroid}'

GET /boundaries/lookup

Point-in-polygon lookup. Given a lat/lng or a postcode, returns the containing electoral district at each level — the "who's my MP, MLA, and city councillor" civic-app pattern in a single call.

Query parameters

Name	Type	Notes
lat	number, 40 – 85	WGS84 latitude. Bounded to roughly Canada-plus-buffer; out-of-range inputs return 400. Pass alongside lng.
lng	number, -145 – -50	WGS84 longitude. Pass alongside lat.
postcode	string	6-char Canadian postcode (K1A0A6) or 3-char FSA (K1A). Alternative to lat/lng; if both are passed, postcode wins. Resolves via Open North in real time — see Postcodes for the licensing posture and FSA caveats.
level	federal | provincial | municipal	Optional — narrows to one level. Omit to look up all three.

At least one of (lat, lng) or postcode must be present, else 400.

Response

{
  "federal": {
    "constituency_id": "federal-electoral-districts-2023-representation-order/35079",
    "name": "Ottawa Centre",
    "level": "federal",
    "province_territory": null,
    "source_set": "federal-electoral-districts",
    "area_sqkm": 40.73,
    "centroid": { "lng": -75.7076, "lat": 45.3915 },
    "effective_from": "2023-01-01",
    "effective_to": null,
    "boundaries_version": "current",
    "boundary_geojson": { "type": "MultiPolygon", "coordinates": [/* … */] }
  },
  "provincial": { "name": "Ottawa Centre", "...": "..." },
  "municipal":  { "name": "Somerset Ward", "...": "..." }
}

Levels with no containing riding come back as null (e.g. lat/lng in an unincorporated area returns municipal: null). When you pass ?level=federal, the other two keys stay null in the response shape.

The simplified boundary_geojson (boundary_simple, ~555 m tolerance) is included so a downstream map widget can render the matched riding without a follow-up call. Membership itself is computed against the full unsimplified geometry — points near district edges classify exactly, even though the rendered polygon is smoothed.

Cache-Control: public, max-age=3600.

Example — Parliament Hill (lat/lng)

curl -s -H 'Authorization: Bearer cpd_live_…' \
  'https://canadianpoliticaldata.org/api/public/v1/boundaries/lookup?lat=45.4242&lng=-75.6989' \
  | jq '{federal: .federal.name, provincial: .provincial.name, municipal: .municipal.name}'

Example — same point via postcode

curl -s -H 'Authorization: Bearer cpd_live_…' \
  'https://canadianpoliticaldata.org/api/public/v1/boundaries/lookup?postcode=K1A0A6' \
  | jq '{federal: .federal.name, provincial: .provincial.name, municipal: .municipal.name}'

Returns the same three matches. The boundary entries are byte-identical between /boundaries/lookup and /postcodes/{postcode} so you can reuse one parser across both endpoints.

{
  "federal":    "Ottawa Centre",
  "provincial": "Ottawa Centre",
  "municipal":  "Somerset Ward"
}

GET /boundaries/{source_set}/{slug}

Single boundary with simplified GeoJSON. The two path params reconstruct constituency_id = source_set + '/' + slug — this keeps slashes out of the URL path so you don't have to URL-encode.

Path parameters

Name	Type	Notes
source_set	string	Open North boundary-set name, e.g. federal-electoral-districts-2023-representation-order or alberta-electoral-districts.
slug	string	Per-set slug. Federal ridings use numeric codes (35079); most provincial sets use kebab-case names (calgary-bow).

Query parameters

Name	Type	Notes
precision	int 1–15	Coordinate precision (decimal places) for the GeoJSON output. Default 6 (≈10 cm at the equator). Lower it to 4 for ~10 m precision and ~half the response size.

Response

{
  "boundary": {
    "constituency_id": "federal-electoral-districts-2023-representation-order/35079",
    "name": "Ottawa Centre",
    "level": "federal",
    "province_territory": null,
    "source_set": "federal-electoral-districts",
    "area_sqkm": 40.73,
    "centroid": { "lng": -75.7076, "lat": 45.3915 },
    "effective_from": "2023-01-01",
    "effective_to": null,
    "boundaries_version": "current",
    "boundary_geojson": { "type": "MultiPolygon", "coordinates": [/* … */] }
  }
}

Returns 404 { code: "not_found" } for unknown source_set/slug combinations.

Cache-Control: public, max-age=3600.

Example

curl -s -H 'Authorization: Bearer cpd_live_…' \
  'https://canadianpoliticaldata.org/api/public/v1/boundaries/federal-electoral-districts-2023-representation-order/35079?precision=4' \
  | jq '.boundary | {name, area_sqkm}'

Recipes

Render every Ontario provincial riding on a Leaflet map

const ridings = await fetch(
  'https://canadianpoliticaldata.org/api/public/v1/boundaries?level=provincial&province_territory=ON&limit=100',
  { headers: { Authorization: 'Bearer cpd_live_…' } }
).then(r => r.json());

for (const r of ridings.items) {
  const detail = await fetch(
    `https://canadianpoliticaldata.org/api/public/v1/boundaries/${r.constituency_id}?precision=4`,
    { headers: { Authorization: 'Bearer cpd_live_…' } }
  ).then(r => r.json());
  L.geoJSON(detail.boundary.boundary_geojson).addTo(map);
}

A bulk-export-style single-file dataset is on the roadmap; the per-riding fetch loop above is the right pattern for now.

"Find my representatives" widget

navigator.geolocation.getCurrentPosition(async (pos) => {
  const { latitude: lat, longitude: lng } = pos.coords;
  const res = await fetch(
    `https://canadianpoliticaldata.org/api/public/v1/boundaries/lookup?lat=${lat}&lng=${lng}`,
    { headers: { Authorization: 'Bearer cpd_live_…' } }
  ).then(r => r.json());

  console.log({
    federal:    res.federal?.name    ?? 'unknown',
    provincial: res.provincial?.name ?? 'unknown',
    municipal:  res.municipal?.name  ?? 'unknown',
  });
});

Caveats

• No Nunavut. Open North doesn't publish boundaries for Nunavut's Legislative Assembly (the upstream is HTML-only). Provincial-level filters for province_territory=NU return zero rows.
• Federal ridings have province_territory = null. Federal ridings span provincial borders by definition; the column reflects what Open North publishes. Filter on level=federal instead.
• Simplified geometry is for rendering, not law. The boundary_simple geometry returned in detail responses is simplified at ~555 m tolerance — visually identical to the full boundary at typical web zoom levels, but not authoritative for edge cases. For exact district membership at a point, use /boundaries/lookup (which queries the full unsimplified geometry server-side).
• Versioning is temporal but currently single-state. All live rows have boundaries_version = "current" and effective_to = null. When redistricting events ship (federal 2033, provincial cycles vary), historical versions will land with effective_to set; the list and detail endpoints will continue to default to the current version.
• Centroid is unweighted. Centroids are computed from the polygon geometry, not population. For population-weighted centroids (campaign targeting, demographic mapping), join your own data.