Working-age mortality in the United States is high, rising, and increasingly differ across counties. Recent efforts to explain the growing disparities in mortality between counties tend to investigate contexts such as state policies and county economic conditions but (a) tend to examine either states or counties, (b) implicitly assume that the contexts that affect mortality rates also affect growing disparities in the rates, and (c) exclude years 2020 and beyond. This study advances understanding of the growing disparities by using data from 1990 to 2024 and kernel reweighting method (DiNardo, Fortin, & Lemieux, 1996, Lemieux 2006) to identify which county and state contexts explain the growing disparities in wages. Our descriptive analyses show that low-mortality counties have diverged from average-mortality counties and that high-mortality counties have diverged from average-mortality counties. This indicates that the explanations for the growing disparities are not simply a deterioration of social safety nets, as sometimes hypothesized in the literature. Descriptive analyses also show that the COVID-19 pandemic greatly exacerbated the divergence of high-mortality counties from average-mortality counties, and that divergence shows no signs of slowing. To explain the growing divergence, including these intriguing patterns, we will use the decomposition approach to identify which state and county contexts are primarily responsible. We will include 20 state and county contexts, such as minimum wage level and share of college graduates, respectively, to the growing disparities.