Economic Research Initiative on the Uninsured CONFERENCE DRAFT The Impact of the Medicaid Expansions of the Late 1990s on the Insurance Coverage of Poor Adolescents

This paper examines the effects of the Medicaid expansions of the late 1990s on the insurance coverage of poor adolescents. To control for the potentially confounding influences of competing trends, I use a difference-in-differences strategy that employs a comparison group of poor younger children who gained public insurance eligibility several years prior to their older peers. Results suggest that the introduction of Medicaid eligibility had a large impact on the insurance coverage of poor adolescents. The probability of being publicly insured at the time of survey rose substantially as a result of the expansions; both the probability of being privately insured and the probability of being uninsured decreased as a result of the expansions. The baseline specification implies that approximately 40% of the increase in public coverage came from those who were previously privately insured. The expansions also reduced the probability of spending any part of the past year without coverage and the probability of spending at least six months of the past year without coverage. Results from various robustness exercises, including a triple-difference specification, yield similar conclusions.