Development and Application of a Cumulative Outage Exposure Index to Assess Sociodemographic Disparities Across United States Counties

Electric power outages significantly impact household physical, mental, and economic wellbeing. When outages repeatedly occur in the same communities over time, they create cumulative exposure burdens that can compound existing detriments. While previous studies have examined individual outage events at the local and regional level, few have quantified the cumulative temporal burden of repeated electricity disruptions at a national scale. Alongside this, few studies have examined how these burdens align with sociodemographic disadvantage. This study develops and applies a novel Cumulative Outage Exposure Index (COEI) using five years (2018–2022) of county-level power outage data from over 3,000 United States counties. The Cumulative Outage Exposure Index (COEI) sums the number of customers reported without power in each 15-minute interval, normalizes this total by the customer base, and averages the result across 60 months to quantify recurring electricity service disruption. Descriptive mapping and cluster analysis of the COEI reveals significant geographic concentration of outage exposure, as well as co-location with sociodemographic disadvantage. Spatial lag models then demonstrate that counties with higher proportions of non-white, elderly, and disabled residents experience significantly greater cumulative outage exposure, even after controlling for spatial autocorrelation. These findings provide national-scale evidence that cumulative electricity outage burdens are geographically concentrated and disproportionately borne by sociodemographically vulnerable communities, highlighting environmental justice concerns as outage frequency continues to increase across the United States.