crosswalk_legacy_county
Legacy county-equivalent FIPS to modern successor crosswalk with population weights. One row per (legacy_county_fips, successor_fips) overlap. Covers the two US county-equivalent transitions that orphan multi-year panels against the current geography dim — Connecticut (2022, 8 legacy counties 09001-09015 → 9 planning regions 09110-09190) and Alaska (2019, Valdez-Cordova 02261 → Chugach 02063 + Copper River 02066). Weights come from exact 2020 town/place populations (CT towns are atomic). Use weight_to_successor to population-weight legacy RATES into a successor; use weight_from_legacy to allocate a legacy COUNT across successors.
overview
21 overlap rows — CT 2022 (8 -> 9 planning regions) and AK 2019 (Valdez-Cordova split).
current vintage — 2022
source & licensing
fields
| name | type | definition |
|---|---|---|
| country_id | string | ISO alpha-2 country code (always 'US' for domestic tables). |
| legacy_county_fipskey | string | 5-character FIPS code of the retired legacy county-equivalent (e.g. 09001 for a Connecticut county, 02261 for Valdez-Cordova). Part of the primary key; joins legacy multi-year panels to their modern successors.Part of primary key. |
| legacy_county_name | string | Name of the legacy county-equivalent that was retired in the transition. |
| overlap_pop_2020 | int64 · count | 2020 Census population of the towns/places shared by this legacy county and this successor — the exact population overlap between the two geographies. Higher values indicate a larger shared population. |
| successor_fipskey | string | 5-character FIPS code of the modern successor geography (Connecticut planning region or Alaska successor borough). Foreign key to dim.counties and part of the primary key.Part of primary key. |
| successor_name | string | Name of the modern successor geography that replaced the legacy county-equivalent. |
| weight_from_legacy | float64 · share (0–1) | Population share used to allocate a legacy COUNT across successors, computed as overlap_pop_2020 / total legacy population. Apply as count_successor = sum(count_legacy * weight_from_legacy); sums to 1 per legacy_county_fips. |
| weight_to_successor | float64 · share (0–1) | Population share used to convert legacy RATES into a successor, computed as overlap_pop_2020 / total successor population. Apply as rate_successor = sum(rate_legacy * weight_to_successor); sums to 1 per successor_fips. |
joins
how to use this table
Population weights from exact 2020 town/place counts; weight_to_successor (rates), weight_from_legacy (counts).
County transitions other than CT-2022 / AK-2019 (not yet covered).