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.

Tables

congressional_districts

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

Column Type Description
id integer Primary key
congress_number integer Congress number (e.g. 118 = 118th Congress)
statename varchar State name
district integer District number (0 for at-large)
startcong numeric Starting Congress number for this district definition
endcong numeric Ending Congress number for this district definition
district_id varchar District identifier
districtsi varchar District significance code
county varchar County name
page varchar Source page reference
law varchar Public law reference
note varchar Notes
bestdec varchar Best decision indicator
finalnote varchar Final note
rnote varchar Redistricting note
lastchange date Date of last change
fromcounty varchar Source county
statefp varchar State FIPS code
geom geometry(MultiPolygon, 3857) District boundary geometry (Web Mercator)
source_file varchar Source filename
imported_at timestamp When this row was imported

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"

PostGIS Spatial Queries

This database exposes 263 PostGIS functions via RPC endpoints. The geom column uses SRID 3857 (Web Mercator).

Common spatial operations

# Check if a point is within a district
curl -X POST "https://benthic.io/ngopen/up_cdmaps/rpc/st_intersects" \
  -H "Content-Type: application/json" \
  -d '{"geom1": {"type": "Point", "coordinates": [-77.0369, 38.9072]}}'

# Get district area (in square meters for SRID 3857)
curl -X POST "https://benthic.io/ngopen/up_cdmaps/rpc/st_area" \
  -H "Content-Type: application/json" \
  -d 'geom_value_here'

Available PostGIS functions (sample)

Function Description
st_intersects Test if two geometries intersect
st_contains Test if geometry contains another
st_distance Distance between geometries
st_area Area of a geometry
st_length Length of a linear geometry
st_transform Transform between coordinate systems
st_buffer Create buffer around geometry
st_centroid Get center point of geometry
st_asgeojson Convert geometry to GeoJSON
st_geomfromtext Create geometry from WKT
st_geomfromgeojson Create geometry from GeoJSON

See the full list of 263 functions at the endpoint root.

PostgREST Query Reference

Filtering

Operator Syntax Example
Equals ?col=value ?statename=eq.California
Not equal ?col=neq.value ?district=neq.0
Greater than ?col=gt.value ?congress_number=gt.110
Less than ?col=lt.value ?congress_number=lt.118
Greater/eq ?col=gte.value ?congress_number=gte.118
Less/eq ?col=lte.value ?congress_number=lte.118
ILIKE ?col=ilike.PATTERN ?statename=ilike.%25new%25
IS null ?col=is.null ?endcong=is.null
IS NOT null ?col=not.is.null ?lastchange=not.is.null
IN ?col=in.(val1,val2) ?statename=in.(California,Texas,New%20York)

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.

Parameter Type Description
lat double precision Latitude
lon double precision Longitude
congress integer Congress number (default: 118)

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.

Parameter Type Description
min_lat double precision Minimum latitude
max_lat double precision Maximum latitude
min_lon double precision Minimum longitude
max_lon double precision Maximum longitude
congress integer Congress number (default: 118)

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}'