Social Data Commons: Employment Access Index (v2.0.0)

⚠ Superseded — this version contains a standardization error. Pre-2020 intensive measures were area-averaged across 2010→2020 census-tract boundary splits rather than replicated, distorting their values. Please use the latest version of this record, which corrects the geographic standardization.

Overview

Employment Intensity (gravity model) from LEHD-LODES WAC job counts and TIGER/Line centroids. E = sum(jobs_i / dist_i^2) with hierarchical distance approximation and 200-mile radius cutoff. This dataset is produced by the Social Data Commons at the University of Virginia as part of the Employment Access data pipeline.

Provenance

Inspired by the Housing + Transportation (H+T) Affordability Index from the Center for Neighborhood Technology (CNT), which used a similar gravity model approach. This implementation computes the index directly from LEHD-LODES Workplace Area Characteristics (WAC) job counts and TIGER/Line Census block centroids.

Coverage

Temporal coverage: 2015–2023 (ACS 5-year estimates)

Geographic levels: County, Tract

Coverage areas: Virginia (statewide)

Methodology

Employment Intensity computed using a gravity model from LEHD-LODES Workplace Area Characteristics (WAC) job counts and TIGER/Line Census block centroids. The index is calculated as the sum of jobs divided by the square of the distance (in miles) from each Census block group to all nearby employment locations, with a hierarchical distance approximation: individual block-level job counts within 34 miles, tract-level aggregates from 34 to 165 miles, and county-level aggregates from 165 to 200 miles. Higher values indicate greater proximity to employment opportunities.

Source Tables

LODES WAC S000 JT00, column C000 (total jobs per Census block)

TABBLOCK20, BG, TRACT, COUNTY shapefiles (INTPTLAT, INTPTLON fields)

Measures (1)

employment_access_index: Employment Access Index (index)

Gravity-based index of employment accessibility using LODES job counts and distance decay (E = sum of jobs / distance squared).

Data Sources

LEHD-LODES Workplace Area Characteristics (accessed 2026)

TIGER/Line Shapefiles (2020 Census Geography) (accessed 2026)

File Format

Data files are provided as xz-compressed CSV (.csv.xz) with the following columns: geoid, region_type, region_name, year, measure, value, moe (margin of error, where available). A measure_info.json file provides per-measure metadata.