Structural Exclusion, Not Labor Markets: Medicaid Expansion and Coverage Pathways among Low-Income Workers in the United States, 2018–2024

Low-income working adults in states that have not expanded Medicaid remain uninsured despite labor force attachment, excluded from public coverage and, for the poorest, from subsidized Marketplace plans. This secondary analysis of Current Population Survey Annual Social and Economic Supplement data (2018-2024; N = 49,325 person-year observations) compared insurance coverage pathways among low-income working adults (ages 19-64, below 150% of the federal poverty level) across Medicaid expansion and non-expansion states over the pre-pandemic, COVID-19 Public Health Emergency, and unwinding periods, using weighted logistic regression with state-clustered standard errors. Employer-sponsored insurance was nearly identical (27.5% vs. 29.5%), yet uninsurance differed by roughly 19 percentage points; divergence was concentrated downstream of employment, where Medicaid enrollment among those without employer coverage differed by 25 points. In adjusted models, residing in an expansion state was associated with a 14- to 20-percentage-point lower probability of uninsurance, robust across specifications and concentrated among the poorest workers. Marketplace coverage was higher in non-expansion states yet did not close the gap. Findings indicate that the uninsurance gap reflects the structural absence of a Medicaid safety net rather than labor market conditions. Future research should examine whether these differences persist as states adopt expansion and as coverage policy shifts.