Under the Affordable Care Act, states have the option to expand Medicaid eligibility to nonelderly people with incomes up to 138 percent of the federal poverty level. As of the time of writing, only 12 states have not done so: Alabama, Florida, Georgia, Kansas, Mississippi, North Carolina, South Carolina, South Dakota, Tennessee, Texas, Wisconsin, and Wyoming. Eleven of the 13 states with the highest uninsurance rates nationwide have not expanded Medicaid. Medicaid expansion remains an important issue for both state and federal policy.

We find that if the 12 nonexpansion states were to fully implement a Medicaid expansion in 2023, 3.7 million fewer people would be uninsured, a reduction of 29.1 percent. Groups with the largest gains in coverage due to Medicaid expansion would include non-Hispanic Black people, young adults, and women, particularly women of reproductive age. New state spending in the current nonexpansion states would be fully or largely offset by savings in other areas and potential new revenue. Several comprehensive analyses of the states that have expanded Medicaid have found that expansion had a net positive impact on many state budgets.