Did the ACA Medicaid expansion save lives?

We estimate the effect of the Affordable Care Act Medicaid expansion on county-level mortality in the first four years following expansion using restricted-access microdata covering all deaths in the United States. To adjust for pre-expansion differences in mortality rates between treatment and control, we use a propensity-score weighting model together with techniques from machine learning to match counties in expansion and non-expansion states. We find a reduction in all-cause mortality in ages 20 to 64 equaling 11.36 deaths per 100,000 individuals, a 3.6 percent decrease. This estimate is largely driven by reductions in mortality in counties with higher pre-expansion uninsured rates and for causes of death likely to be influenced by access to healthcare. A cost-benefit analysis shows that the improvement in welfare due to mortality responses may offset the entire net-of-transfers expenditure associated with the expansion.