WILMINGTON, DELAWARE
Reconstructed HOLC Residential Security Map · 1940 Census
Grade Distribution
B: 1 C: 71 (63%) D: 41 (36%)
1940 Census
Population 109,010
Black / African American 13,852 (12.7%)
Foreign-Born 10,119 (9.3%)
Enumeration Districts 113
Racial Sorting (1940)
Grade C Grade D Ratio
% Black 1.2% 31.5% 27.3x
Median Income $1,216 $713 1.70x
85-Year Persistence
Black Denial Rate (2022)
  In predicted C areas 17.7%
  In predicted D areas 31.6%
  D/C Ratio 1.79x
Neighborhoods predicted to have been redlined in the 1940s still show elevated mortgage denial 85 years later... in a city HOLC never surveyed.
Model
Ordered Probit + GBM Ordinal Ensemble
Trained on 2,130 HOLC-graded areas (39 mid-Atlantic cities)
Source: THOLCADS (Markley 2023), IPUMS 1940 Full-Count
ED Polygons: Huang et al. (2025)
HMDA: CFPB 2022 LAR
Mean confidence: 81.7%
BARSS Research, 2026
THE INVISIBLE REDLINE
Reconstructing What HOLC Would Have Done to Wilmington, 1935-1940