California Center for Population Research

During the 1990s many states extended Medicaid eligibility to low-income parents who were not receiving welfare. We evaluate the effects of those expansions on health insurance coverage. To account for unobservable differences between expansion states and non-expansion states that may be correlated with both policy decisions and insurance coverage, we employ a within-state difference-in-difference technique that makes use of data only from expansion states. We find that the parental eligibility expansions increased Medicaid coverage of mothers with only small effects on private coverage. The expansions also increased the coverage of children, presumably by raising the benefit to the family of applying for coverage. We find substantial racial and ethnic differences in the effects of the expansions. As a result, the expansions help reduce racial and ethnic gaps in insurance coverage, particularly for adults.