PROJECT SUMMARY/ABSTRACT Since 2013, inequities in firearm-related mortality between Black and White youth (ages 1-19) in the United States (US) have widened. A critical, overlooked aspect of increasing youth firearm-related mortality is a fourfold increase in firearm-related deaths among Black rural youth. This represents a dramatic reversal from the historical pattern of lower firearm-related mortality in rural Black youth compared to their urban counterparts. Four key macro-level factors-structural racism, socioeconomic disadvantage, firearm availability, and population composition (e.g., migration, age structure}--likely influence recent spatio-temporal trends in Black youth firearm-related mortality. However, their precise contributions remain unknown. This project aims to identify state- and county-level factors driving this epidemic of firearm-related mortality among Black youth, particularly in rural areas. This project has three specific aims. Aim 1: Investigate how changes in structural racism, socioeconomic disadvantage, firearm availability, and population composition contribute to increasing Black-White inequities in youth firearm-related mortality in the US in the aggregate. Aim 2: Compare spatio-temporal patterns in the distribution of these determinants between counties with higher Black youth firearm-related mortality versus those with lower rates, separately for rural and urban counties. Aim 3: Explore the extent to which within-county changes in these macro-level factors over time influence within-county increases in firearm-related mortality among Black rural youth. We will use CDC restricted-use data for youth firearm-related mortality (1989-2023). A decedent's county of residence will be linked to county-level demographics from the American Community Survey, population estimates from the US Census Bureau, and state-level gun ownership data from RAND. Using decomposition techniques, we will examine how each of the four macro-level factors changed over the course of our study period and the extent to which change in each factor contributes to changes in Black-White inequities in youth firearm-related mortality. Next, we will assess the spatio-temporal distribution of these determinants, comparing counties with higher Black youth firearm-related mortality to those with lower rates, separately for rural and urban areas. Finally, fixed-effects models will assess the relationship between within-county changes in macro-level factors and within-county changes in rural Black youth firearm-related mortality. The long-term goal is to eliminate inequities in youth firearm-related mortality. This timely and urgent project aligns with the goals of NICHD and its Population Dynamics Branch to improve child and adolescent health and reduce health disparities. It will also provide insights into how different social and demographic factors operating at multiple levels contribute to inequities in youth firearm-related mortality. By employing in...