Data from United States Census.
Map and API infrastructure based on represent-boundaries (originally by Chicago Tribune/OpenNorth) and represent-maps.
This page demonstrates how to access the GIS API and how to display colorful map layers for the United States Congressional Districts (2012; Census BAS) data hosted here.
Here is the metadata stored with this layer:
Authority: United States Census
Domain: United States
Last Updated: Oct. 19, 2012 (layer) / Oct. 19, 2012 (geography)
Source URL: https://www.census.gov/rdo/data/113th_congressional_and_new_state_legislative_district_plans.html
This is a demo page for using either Google Maps API v3 or OpenLayers with Open Street Map [Toggle Google/OSM]. View the source to see how it’s done.
Click on the map or hover over the map (Google Maps only) to see what’s there.
View the demo map page for the entire layer.
The geospatial information here is modeled in BoundarySets, Boundaries, MapLayers, and MapLayerBoundaries. You are looking at the page for the MapLayer named cd-2012, which is based on the BoundarySet named cd-2012.
A BoundarySet is a group of geographic regions, like districts or wards.
The metadata fields of a BoundarySet are largely user-supplied strings.
|name_plural||Category of boundaries, e.g. "Community Areas".|
|name_singular||Name of a single boundary, e.g. "Community Area".|
|authority||The entity responsible for this data's accuracy, e.g. "City of Chicago".|
|domain||The area that this BoundarySet covers, e.g. "Chicago" or "Illinois".|
|source_url||The url this data was found at, if any.|
|notes||Notes about loading this data, including any transformations that were applied to it.|
|licence_url||The URL to the text of the licence this data is distributed under|
|last_updated||The last time this data was updated from its authority (but not necessarily the date it is current as of).|
|extent||The bounding box of the boundaries in EPSG:4326 projection, as a list such as [xmin, ymin, xmax, ymax]. (Optional.)|
A Boundary is a single district. It is stored as a MultiPolygon internally, which means the district may be made up of multiple geographically disjoint parts. All coordinates are in the WGS 84 (EPSG:4326) spatial reference system.
The metadata fields of a Boundary are:
|boundary_set_name||Category of boundaries that this boundary belongs, e.g. "Community Areas".|
|name||The name of this boundary, e.g. "Austin".|
|metadata||The complete contents of the attribute table for this boundary from the source shapefile, structured as json.|
|external_id||The boundaries' unique id in the source dataset, or a generated one.|
|extent||The bounding box of the boundary in EPSG:4326 projection, as a list such as [xmin, ymin, xmax, ymax]. (Optional.)|
|centroid||The centroid (weighted center) of this boundary in EPSG:4326 projection. (Optional.)|
There is no API for MapLayers and MapLayerBoundaries at this time.