Abstract Background Recent Medicaid expansions have rekindled the debate around
private insurance “crowd‐out.” Prior research is limited by short‐time horizons and state‐
specific analyses. Our study overcomes these limitations by evaluating 20 years of Medicaid
expansions across the entire United States. Methods We obtain data from the US Census
Bureau for all US states and District of Columbia for private insurance coverage rates of
adults 18–64 for years 1999–2019. After estimating a naïve, staggered Two‐way fixed …

Recent Medicaid expansions have rekindled the debate around private insurance “crowd-
out”. Prior research is limited by short-time horizons and state-specific analyses. Our study
overcomes these limitations by evaluating twenty years of Medicaid expansions across the
entire United States. We obtain data from the US Census Bureau for all US states and DC for
private insurance coverage rates of adults 18-64, for years 1999-2019. After estimating a
naïve, staggered Two-Way Fixed Effects Difference-in-Differences regression model, we …