Administrative boundaries are the geometries that some authority — a national mapping agency, a census bureau, a media-measurement vendor, a utility, a publisher — has declared to exist, and that authority's decision is the geometry's only source of truth. This distinguishes the family from arbitrary polygons: a county line does not move because a better model draws it differently, and disputing it means petitioning the agency, not re-running an algorithm. Every member of this family is consumed as a partition — reporting, budgeting, tax, and compliance logic downstream assumes every point on Earth belongs to exactly one instance of a given level, which is why the conversion path for this family (below) defaults to producing a true partition rather than a proportional split.
- Cardinality
- Partition — every location belongs to exactly one instance per level
- Governed by
- A national, statistical, or licensing authority per level (Census, USPS, Nielsen, ISO)
- Not a geometry
- The id (FIPS, GEOID, DMA code, ZIP) — only the resolved boundary is
- Converts via
- Center-contained or max-overlap polyfill into a cell-to-region partition
Members
| Member | What it is | Typical id / namespace |
|---|---|---|
| Country | National boundary | ISO 3166-1 alpha-2/3 |
| State / province | First-level subdivision | FIPS (US), ISO 3166-2 |
| County | Second-level subdivision | 5-digit FIPS (US) |
| Municipality / borough | City, town, or borough-level unit | Local/vendor id, often no federal standard |
| Postal code | USPS/national mail delivery area | ZIP (US), postcode (UK) |
| Census geography | Tract, block group, block | GEOID (US Census/TIGER) |
| DMA / media market | Nielsen-defined media market | DMA code (proprietary) |
| NUTS or equivalent | EU statistical region hierarchy | NUTS 1/2/3 code |
| Electoral district | Voting/representation boundary | State/national election-authority id |
| School district | Education-service boundary | NCES district id (US) |
| Service territory | Utility or franchise service area | Utility-internal id |
| Publisher-defined market | A media owner's own named market | Publisher-internal label |
Required metadata
| Field | Why it's required |
|---|---|
| Boundary source | Different agencies draw the "same" boundary differently (e.g. Census TIGER vs. a commercial vendor's county file) |
| Vintage | Every level in this family is redrawn on its own schedule — counties rarely, DMAs and postal areas often |
| CRS | Vendor shapefiles frequently arrive in a projected CRS and must be reprojected to EPSG:4326 before any H3 work |
| Id namespace | "12" means nothing without knowing whether it's a FIPS state code, a DMA code, or a publisher's internal label |
Common risks
"36061" is a string. It is not a shape until it is resolved against a
specific boundary file at a specific vintage. Two systems holding the same
FIPS code can disagree about the polygon it resolves to if one is running a
2020 vintage and the other a 2024 vintage — the id never changes even when
the boundary under it does. This is the single most common source of silent
misassignment in this family; see
requested vs. executed geography.
Beyond that structural risk, four failure modes recur across this family:
vintage drift (DMA and postal boundaries move on cycles measured in
years, not decades — a crosswalk built against a stale vintage misassigns
every cell near a boundary that has since shifted); leading-zero loss
(FIPS and GEOID strings — "01001" for Autauga County, Alabama — are
numeric-looking but not numbers, and an integer cast silently truncates the
leading zero, producing a code that either doesn't match anything or
matches the wrong region); ZIP-is-not-a-polygon (a US ZIP code is a USPS
delivery-route abstraction with no authoritative boundary of its own — any
"ZIP polygon" in circulation is a third party's ZCTA approximation, and
must be labeled and sourced as such rather than treated as ground truth);
and licensing (DMA boundaries specifically are Nielsen's proprietary
IP — redistributing a raw DMA shapefile, or a cell-to-DMA crosswalk derived
from one, without the appropriate license is a legal exposure, not just a
data-quality one).
How it converts to H3
Administrative boundaries are polyfilled into H3 as a partition — one region id per cell, by center-containment or max-overlap assignment — on administrative polygon to H3. When the requirement is proportional splitting instead (population or spend divided across regions a cell straddles), use the weighted variant on H3 to administrative crosswalk. If what you're actually holding is a bare id rather than a polygon, that is not this family at all — see platform identifiers.