https://benthic.io/ngopen/up_cdmaps/ – Congressional district maps/boundaries

The core theme of this database, created using UCLA Polysci’s excellent congressional district dataset, is boundaries of congressional districts historic and current.

At a glance

Tables

congressional_districts

Historical and current U.S. congressional district boundaries with geometry. One row per district definition from Congressional redistricting data.

Example queries

# Get all districts for a state in the current Congress
curl "https://benthic.io/ngopen/up_cdmaps/congressional_districts?statename=eq.California&congress_number=eq.118&select=id,statename,district,congress_number"

# Get all at-large districts
curl "https://benthic.io/ngopen/up_cdmaps/congressional_districts?district=eq.0&congress_number=eq.118&select=statename,district"

# Get all districts for a specific Congress number
curl "https://benthic.io/ngopen/up_cdmaps/congressional_districts?congress_number=eq.118&select=id,statename,district&order=statename,district&limit=500"

# List available Congress numbers
curl "https://benthic.io/ngopen/up_cdmaps/congressional_districts?select=congress_number&groupby=congress_number&order=congress_number"

# Get a specific state + district
curl "https://benthic.io/ngopen/up_cdmaps/congressional_districts?statename=eq.Texas&district=eq.7&congress_number=eq.118"

# Count districts per state for a Congress
curl "https://benthic.io/ngopen/up_cdmaps/congressional_districts?select=statename,count&congress_number=eq.118&groupby=statename"

Working with geometries directly

You can request raw geometry as GeoJSON (select=id,statename,district,geom) and run any further geometric analysis client-side (e.g. with Shapely, Turf.js, or QGIS). If you join geom polygons against geocoded point columns from other NGOpen datasets, remember those points are EPSG:4326 while these polygons are EPSG:3857 — reproject before comparing (ST_Transform server-side, or an equivalent in your GIS library).

PostgREST query reference

Filtering

Selecting columns

?select=id,statename,district,congress_number,statefp

Ordering

?order=congress_number.desc,statename.asc,district.asc

Pagination

?limit=100&offset=200

Counting

Prefer: count=exact

Key relationships

This is a single-table database. Cross-reference to other benthic.io datasets:

• USAspending — match statefp + district to ref_population_cong_district for population data; use financial_accounts_by_awards to find spending in a district
• USP CL — legislator_terms contains state and district columns that match this table
• IRS NG — geocoded nonprofit locations can be spatial-joined to districts via geom

Spatial RPC functions

rpc_find_district

Find the congressional district for a lat/lon point. Returns the district that contains the given coordinate.

Example queries

# Find district for Washington DC coordinates
curl -X POST "https://benthic.io/ngopen/up_cdmaps/rpc/rpc_find_district" \
  -H "Content-Type: application/json" \
  -d '{"lat": 38.9072, "lon": -77.0369}'

# Find district for a specific congress
curl -X POST "https://benthic.io/ngopen/up_cdmaps/rpc/rpc_find_district" \
  -H "Content-Type: application/json" \
  -d '{"lat": 34.0522, "lon": -118.2437, "congress": 117}'

rpc_districts_in_bbox

Find all districts intersecting a bounding box. Useful for map viewport queries.

Example queries

# Get districts in a viewport bounding box
curl -X POST "https://benthic.io/ngopen/up_cdmaps/rpc/rpc_districts_in_bbox" \
  -H "Content-Type: application/json" \
  -d '{"min_lat": 32.0, "max_lat": 36.0, "min_lon": -120.0, "max_lon": -114.0}'

Data sources

This dataset is not refreshed. The source is a fixed historical series, and the pipeline hashes each archive so a rerun is a no-op rather than a re-fetch.

SRID. Geometry is stored in EPSG:3857 (Web Mercator) to match the serving database; the source shapefiles are EPSG:4269 (NAD83). Every other spatial dataset in the collection is EPSG:4326, so a spatial join against irs_ng or samer needs an explicit ST_Transform first. A naive ST_Intersects will return wrong answers silently.

Related

• Swagger explorer — interactive API browser for /ngopen/up_cdmaps
• Signed manifest — every relation, column, and licence, signed with the publisher’s Ed25519 key
• Pipeline README — how this dataset is actually built
• BDP specification — what the manifest signature proves, and how to verify it offline
• Documentation map — every dataset on benthic.io and where its documentation lives
• APIs overview — join paths between datasets and worked cross-collection queries
• Also in NGOpen: USAspending, SAM Entity Registry, IRS Nonprofits, Congress Legislators
• In Parts: NHTSA vPIC Vehicle Information