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FIPS / SAME Location Code Data Sources

The county and SAME location codes baked into app_utils/fips_codes.py (US_FIPS_COUNTY_TABLE, COUNTY_SUBDIVISIONS, US_FIPS_LOOKUP) are derived from authoritative U.S. Government sources. This document records those sources so the table can be regenerated or audited as the underlying geographies change (Connecticut planning regions, Alaska borough splits, new municipios, etc.).

Authoritative U.S. Government sources

1. SAME / EAS location codes — NOAA / National Weather Service

The canonical, EAS-operational list of SAME (Specific Area Message Encoding) location codes is published by the National Weather Service. It includes every county/parish/borough plus the marine and offshore Z-zones that NWR/EAS receivers can decode.

Source URL Notes
NWR SAME index (HTML, browseable by state) https://www.weather.gov/nwr/counties Human-readable master index.
Per-state SAME tables (plain text) https://www.weather.gov/nwr/SAMECountyTextFiles/<XX>SAME.txt (e.g. OHSAME.txt) Authoritative text format used by station engineers.
NWS public-zone shapefiles https://www.weather.gov/gis/PublicZones County / zone boundaries with the SAME/UGC code as an attribute.

47 CFR § 11.31 (FCC Part 11) defines the format of the SAME location code (PSSCCC, with leading portion digit P) but defers to the U.S. Census Bureau for the underlying SS+CCC values.

2. County FIPS / ANSI codes — U.S. Census Bureau

The 5-digit county FIPS values in US_FIPS_COUNTY_TABLE come from the Census Bureau, which maintains the list as ANSI INCITS 31. NIST's original FIPS PUB 6-4 was withdrawn in 2008 and Census is now the official keeper.

| Source | URL | Notes | | --- | --- | --- | | national_county.txt (current vintage) | https://www2.census.gov/geo/docs/reference/codes/files/national_county.txt | One row per county; pipe-delimited STATE|STATEFP|COUNTYFP|COUNTYNAME|CLASSFP. | | national_county2020.txt (2020 vintage) | https://www2.census.gov/geo/docs/reference/codes2020/national_county2020.txt | Includes the 2022 Connecticut planning-region restructuring and Alaska's 2008/2013/2015 reorganizations. | | Gazetteer files (centroids, ANSI) | https://www.census.gov/geographies/reference-files/time-series/geo/gazetteer-files.html | Adds latitude/longitude and ANSI codes for cross-reference. |

The territory entries (PR, USVI, Guam, American Samoa, CNMI) live in the same national_county.txt file; the freely-associated states (FSM 64, RMI 68, Palau 70) are not U.S. territory and are intentionally omitted.

3. County subdivisions — U.S. Census Bureau

The optional subdivisions surfaced through COUNTY_SUBDIVISIONS / US_FIPS_SUBDIVISIONS come from the Census Bureau's MCD (minor civil division) Gazetteer file:

These map to SAME portion digits 1-9 via the P digit defined in 47 CFR § 11.31 and P_DIGIT_LABELS in app_utils/fips_codes.py.

Regenerating the embedded table

US_FIPS_COUNTY_TABLE is intentionally embedded as a literal string so the package has no runtime dependency on a network fetch or shipped data file. To refresh it:

  1. Download the current national_county.txt from Census (link above).
  2. Drop rows for the freely-associated states (FIPS state codes 64, 68, 70) and any non-SAME entries.
  3. Reformat each row as STATEFP+COUNTYFP|ST|County Name (e.g. 29183|MO|St. Charles County). Preserve diacritics where Census uses them (e.g. Bayamón, Doña Ana, Mayagüez).
  4. Cross-check the resulting set against the relevant per-state NWS *SAME.txt files; any code present in both must match.
  5. Run the FIPS-related tests (pytest tests/test_eas_monitor_fips_matching.py tests/test_detect_county_wide_false_positive.py tests/test_audio_detail_locations.py) before committing.

Known intentional deviations

  • DC (11001) is labeled District of Columbia in this repo for clarity, whereas Census labels the county Washington (the District itself is the parent state). The NWS SAME list also uses District of Columbia, which we follow.

  • Alaska: this repo carries the post-2013/2015/2019 borough/census-area splits (Hoonah-Angoon 02105, Kusilvak 02158, Petersburg 02195, Prince of Wales-Hyder 02198, Skagway 02230, Wrangell 02275) and omits the retired predecessors (02201, 02232, 02270, 02280).

  • South Dakota: 46102 Oglala Lakota County is included instead of the renamed 46113 Shannon County (renamed by SD legislature in 2015).

  • Marine / offshore Z-zones from the NWS list (e.g. LEZ###, PZZ###, AMZ###, GMZ###) are managed by the runtime NWS zone catalog (nws_zones table, fed by NOAA shapefiles) rather than embedded in the US_FIPS_COUNTY_TABLE string literal — they use alphabetic UGC prefixes that don't fit the numeric FIPS grid as parent rows. See NWS_ZONE_CATALOG.md for the authoritative marine sources, the DBF schema, and every supported mechanism for refreshing the catalog (CLI, admin UI upload, env var, asset auto-detect).

    However, the numeric PSSCCC codes that marine alerts carry on the SAME wire (e.g. 077156 for an American Samoa marine zone) still need to appear in the admin FIPS picker so operators can configure marine monitoring. app_utils/fips_codes.py therefore declares two small marine-specific tables:

    • MARINE_PREFIX_TO_SAME_STATE — UGC prefix → SAME SS digits. All 15 marine prefixes (PZ=57, PK=58, PH=59, PS=61, PM=65, AN=73, AM=75, GM=77, LS=91, LM=92, LH=93, LC=94, LE=96, LO=97, SL=98) are populated from the NWS Coastal and Offshore Marine Codes Listings for EAS and NWR Applications §6. The GM row is additionally cross-verified against an on-air SMW header (077650/077633/077632/ 077631 ↔ GMZ650/GMZ633/GMZ632/GMZ631).
    • MARINE_AREA_LABELS — geographic-area name per prefix, following the same NWS table.

    When NWS publishes a new marine prefix in the future, tools/match_same_to_zone.py can be used to confirm the SS digit empirically against any received alert before extending the table.

    get_marine_state_tree() queries nws_zones for rows whose state_code matches a configured prefix and emits a "state" entry per prefix (counties = its marine zones, codes = the 6-digit numeric SAME). get_extended_state_county_tree() composes the static US tree with this dynamic marine tree and is what the admin dashboard hands to the FIPS picker template.

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This document is served from docs/reference/FIPS_DATA_SOURCES.md in the EAS Station™ installation.