PROJECT SUMMARY Black Americans have the highest hypertension (or high blood pressure, HBP) rates in the world, with stark racial disparities between Black and White adults that have persisted for decades and at the highest cost to society of all cardiovascular conditions. The underlying cause of HBP disparities is unknown, and previous studies have mostly focused on individual-level behaviors, stressors, and physiologic risk factors leaving a missed opportunity to uncover and address the root causes of these disparities. Structural racism may be a root cause of HBP disparities and, as such, HBP disparities will persist if structural racism is not addressed. Thus, to eliminate HBP disparities, we must first investigate if structural racism is a fundamental cause and use longitudinal studies to explore the pathways through which structural racism influences HBP risk factors and disparities. Using a novel 5-domain measure of structural racism, our previous cross-sectional studies have demonstrated that greater structural racism is associated with higher BMI, one behavioral risk factor for HBP; however, this work has left gaps in understanding how structural racism is related to other risk factors for HBP, as well as questions about the timing and geographic scales at which structural racism operates. We seek to fill these gaps in responding to RFA-MD-21-004’s request for “observational research to understand the role of structural racism…in causing and sustaining health disparities” for HBP. Our goal is to conduct a multi-level national study to investigate associations between our novel multi-dimensional measure of county-level structural racism (CSR) and: physiologic, behavioral, and structural risk factors for HBP (Aim 1), HBP incidence, prevalence, and severity (Aim 2), and how much counties could save in HBP healthcare costs if CSR was eliminated (Aim 3). We leverage pre-existing resources that are uniquely available to us: (a) our published County Structural Racism Scale, (b) US News & World Report hospital rankings of healthcare quality, and (c) longitudinal behavioral and biomarker HBP data from 30,239 Black and White adults across the US in the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort. We expand beyond previous studies by using a multi-domain measure of structural racism, applying it to longitudinal health data that allows us to assess exposure to structural racism at multiple times in the lifecourse, and quantifying how much structural racism costs counties in HBP healthcare spending when it goes unaddressed. We will translate our findings into policy briefs targeted toward county-level executives in the US. Our team of experts in CVD disparities, social and clinical epidemiology, and health economics, with representation from REGARDS, two Hopkins disparities centers, Hopkins’ CVD Epidemiology, and former county leaders, are well- equipped to execute this New Investigator application. Our results will offer...