Jim P Stimpson, Fernando A Wilson

The Affordable Care Act's Medicaid expansion provisions have been credited with overall improvements in insurance coverage, access to care, and health. However, recent studies have found that racial and ethnic disparities in coverage have persisted in spite of these improvements. We used data for the period 2010-15 from the American Community Survey about adults ages 19-64 to study the impact of Medicaid expansion on insurance coverage among US natives, naturalized citizens and noncitizen immigrants. We found that uninsurance decreased among US natives, naturalized citizens, and noncitizen immigrants after 2013. The percentage of uninsured noncitizens decreased from 69.6 percent in 2010 to 53.5 percent in 2015. However, uninsurance rates remained high for noncitizens in 2015, with 44.9 percent of them uninsured in expansion states, compared to 16.3 percent of natives. A triple-differences analysis suggested that among natives and noncitizens, 5.6 percent and 5.0 percent, respectively, of the drop in uninsurance were attributable to Medicaid expansion. However, decreases in uninsurance among naturalized citizens could not be attributed to Medicaid expansion. Although health insurance coverage improved significantly for natives, naturalized citizens, and noncitizens, substantial disparities in insurance coverage persisted for noncitizen immigrants.