Mapping Inequality: Redlining in New Deal America

This dataset contains the "Home Owners' Loan Corporation" (HOLC) grades for neighborhoods in cities across the United States. These maps, created in the 1930s, were used to grade the "security" of real estate investments, leading to the practice known as redlining.

Source

• Project: Mapping Inequality: Redlining in New Deal America
• Authors: Robert K. Nelson, Laedale Winling, Richard Marciano, Nathan Connolly, et al.
• Institution: Digital Scholarship Lab, University of Richmond
• License: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International

Data Format

The dataset is available in the following formats:

• GeoParquet: s3://public-mappinginequality/mappinginequality.parquet (Full dataset)
• PMTiles: s3://public-mappinginequality/mappinginequality.pmtiles (For web mapping)
• H3 Hexagons: s3://public-mappinginequality/hex/ (Partitioned by h0)

Data Dictionary

HOLC Grades

The grade column contains the core classification:

• A (Green): "Best" - Upper-class, wealthy neighborhoods.
• B (Blue): "Still Desirable" - Sound working-class neighborhoods.
• C (Yellow): "Definitely Declining" - Neighborhoods with "infiltration" of lower-grade populations.
• D (Red): "Hazardous" - Neighborhoods with high populations of racial/ethnic minorities or "undesirable" features.

Usage Examples

DuckDB

1-- Explore redlining grades by city
2SELECT city, state, grade, COUNT(*) as n
3FROM read_parquet('https://s3-west.nrp-nautilus.io/public-mappinginequality/mappinginequality.parquet')
4GROUP BY city, state, grade
5ORDER BY city, grade;
1-- Explore redlining grades by city
2SELECT city, state, grade, COUNT(*) as n
3FROM read_parquet('https://s3-west.nrp-nautilus.io/public-mappinginequality/mappinginequality.parquet')
4GROUP BY city, state, grade
5ORDER BY city, grade;

MapLibre GL JS

The PMTiles source-layer name is redlining.

1map.addSource('redlining', {
2  type: 'vector',
3  url: 'pmtiles://https://s3-west.nrp-nautilus.io/public-mappinginequality/mappinginequality.pmtiles'
4});
5
6map.addLayer({
7  id: 'redlining-fill',
8  type: 'fill',
9  source: 'redlining',
10  'source-layer': 'redlining',
1map.addSource('redlining', {
2  type: 'vector',
3  url: 'pmtiles://https://s3-west.nrp-nautilus.io/public-mappinginequality/mappinginequality.pmtiles'
4});
5
6map.addLayer({
7  id: 'redlining-fill',
8  type: 'fill',
9  source: 'redlining',
10  'source-layer': 'redlining',

Citation

Robert K. Nelson, Laedale Winling, Richard Marciano, Nathan Connolly, et al., "Mapping Inequality," American Panorama, ed. Robert K. Nelson and Edward L. Ayers, accessed [Date], https://dsl.richmond.edu/panorama/redlining/