This study examines the association between prior incarceration and health insurance status and whether living in a state adopting the Affordable Care Act (ACA) Medicaid expansion moderates this relationship. Data are from the National Longitudinal Study of Adolescent to Adult Health (Wave I 1993-1994, Wave IV 2008, and Wave V 2016-2018; N=8,965). Multiple logistic regression with multiplicative interaction terms were performed to assess the relationship between previous incarceration and ACA Medicaid expansion on (1) being insured and (2) being on public health insurance. Analyses were performed in 2023. Findings demonstrate a positive and statistically significant interaction in the association between previous incarceration and living in a state with ACA Medicaid expansion on having public health insurance (OR=2.402; 95% CI=1.257, 4.588). The ACA Medicaid expansion was associated with a greater likelihood of public health insurance coverage for formerly incarcerated persons in the U.S. These findings suggest that Medicaid expansion could be critical in improving health insurance coverage among formerly incarcerated individuals who are a population that is more likely to be uninsured.