economy_industrial_concentration_county_year
HHI and predominant sector from NAICS-2 private-sector employment shares (E2). Tier A. Powers scorecard concentration metrics.
overview
3,221 counties. QCEW NAICS-2 private sector coverage.
current vintage — 2024
history — NAICS-based: 2001-present; SIC-based pre-2001
source & licensing
fields
| name | type | definition |
|---|---|---|
| country_idkey | string | ISO alpha-2 country code (always 'US' for domestic tables).Part of primary key. |
| county_idkey | string | 5-character FIPS code identifying the county.Part of primary key. Joins dim.counties on county_id. |
| economic_concentration_hhi | float64 · index (0–1) | Herfindahl-Hirschman Index computed as the sum of squared private-sector employment shares across NAICS-2 sectors within the county. Higher values indicate greater concentration of employment in fewer industries; a value of 1 represents complete specialization in a single sector. |
| predominant_sector | string | NAICS 2-digit sector code and label for the private-sector industry with the largest employment share in the county-year. |
| predominant_sector_share | float64 · share (0–1) | Fraction of total private-sector employment accounted for by the predominant sector. Higher values indicate that employment is more concentrated in this leading industry. |
| runner_up_sector | string | NAICS 2-digit sector code and label for the private-sector industry with the second-largest employment share in the county-year. |
| runner_up_sector_share | float64 · share (0–1) | Fraction of total private-sector employment accounted for by the runner-up sector. Together with predominant_sector_share, captures the two-sector employment concentration. |
| state_idkey | string | 2-character FIPS code identifying the state.Part of primary key. Joins dim.states on state_id. |
| yearkey | int64 | Reference year of the observation.Part of primary key. |
joins
how to use this table
HHI = SUM((employment_share_naics2_i)^2) over private NAICS-2 supersectors. predominant_sector = NAICS-2 with largest share. predominant_sector_share = max share. Government own_code='1','2','3' excluded.
Cross-NAICS-revision comparison (NAICS 2002, 2007, 2012, 2017, 2022 introduce small reclassifications); narrow industry concentration (use NAICS-4 or NAICS-6, not loaded here).
HHI computed at NAICS-2 only; misses concentration in narrow industries. Suppression in small cells biases HHI downward.