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Uninsured rate dips linked to Medicaid expansion, outcomes

Commonwealth Fund researchers said dips in statewide uninsured rates are likely due to Medicaid expansion and the ACA marketplace plans.

Sara Heath
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Published: 18 Jun 2025

A new report from the Commonwealth Fund shows improvements in the nation's uninsured rate between 2013 and 2023, underscoring the role the Affordable Care Act and its provisions for Medicaid expansion made in boosting nationwide health outcomes.

The "2025 Scorecard on State Health System Performance" uses the most recent data available to quantify health insurance coverage rates in individual states, as well as the District of Columbia. It also ranks states on metrics related to healthcare quality, such as access and affordability, prevention and treatment, avoidable hospital use and costs, health outcomes and behaviors and health equity.

The report outlines a period of growth in health insurance coverage nationwide. From 2013 to 2023, the U.S. saw uninsurance rates drop from 20.4% to 11%.

But those coverage gains weren't distributed equally across the country, creating a regional patchwork of healthcare quality, particularly in terms of healthcare access and affordability.

"This report shows how much progress states have made expanding health coverage for millions through Medicaid expansion and subsidized marketplace coverage. But these gains are fragile," Sara R. Collins, a study author and Commonwealth Fund senior scholar and vice president for Health Care Coverage and Access, said in an emailed press release.

"If Congress allows the extra premium subsidies passed during the pandemic to expire and makes it harder to get and keep Medicaid and marketplace coverage, the number of uninsured will climb toward pre-ACA levels, when 49 million people lacked health insurance. States already facing the biggest challenges will fall even further behind."

The uninsured rate went down in every state since 2013

The nation's nearly 10 percentage-point drop in uninsurance was driven, in large part, by the ACA, the Commonwealth Fund researchers indicated. The legislation, signed into law in 2010 and enacted in 2014, provided an option for states to expand Medicaid and created a health insurance marketplace that provides subsidies to purchase health plans.

Overall, 44 million people were enrolled in ACA coverage expansions by 2024. This includes 21.4 million people who got coverage through a marketplace plan, 21.3 million who received Medicaid coverage through Medicaid expansion and 1.3 million people covered through the Basic Health Program that some states opted to set up.

However, the researchers flagged state-by-state coverage disparities.

"People's health insurance coverage is directly tied to the policy decisions their states have made, as well as decisions the federal government has made," they explained. "The states with the lowest uninsured rates and the biggest improvement since 2013 are those that have fully implemented the Affordable Care Act, including its Medicaid eligibility expansion."

California went from 24% uninsured in 2013 to just 9% in 2023 and Louisiana dropped from 24.7% uninsured to 10%, both representing some of the biggest reductions in uninsured rates during the decade. Both states opted to expand Medicaid.

The smallest uninsured rate drop was in Massachusetts, likely because the state already boasted a lower-than-average rate in 2013. As a result of the ACA, uninsurance in Massachusetts dropped from 5.4% in 2013 to 3.6% in 2023. Right now, the District of Columbia has the lowest uninsurance rate of 3.4%.

But despite improvements in state uninsurance rates, the Commonwealth Fund still found some states with high uninsurance rates.

In 2023, Texas was an outlier for its uninsurance rate, which came in at 21.6%. The next-highest uninsured rate was for Oklahoma, but that was still nearly 5 percentage points lower than the rate in Texas. In Oklahoma, the uninsured rate is 16.3%.

Better health insurance enrollment numbers benefit outcomes

The Commonwealth Fund noted that better insurance coverage, regardless of payer type, has led to better health outcomes. For example, Medicaid expansion and the higher number of people covered by the public payer have resulted in an estimated 27,000 lives saved.

This principle held true in a state-by-state breakdown. For example, Massachusetts, Hawaii, New Hampshire, the District of Columbia and Vermont are among the best-performing states in terms of healthcare access. These states are also among the top 10 states with the lowest uninsured rate.

Conversely, the states that had not yet expanded Medicaid were also among the worst in terms of healthcare access. Texas, Mississippi and Georgia are low performers for healthcare access and also have some of the highest uninsured rates.

"About 1.4 million uninsured people in the 10 states that haven’t expanded Medicaid fall in the so-called coverage gap: they earn too little to be eligible for marketplace coverage but also are not eligible for their state's existing Medicaid program, which is generally only for parents with very low income," the report authors said.

Notably, uninsured rates are likely to increase as Congress mulls over changes to Medicaid and the ACA that could lead to coverage loss.

"Recent policy developments, however, could lead to fewer people with health insurance in all states," the report authors pointed out.

"These include proposed Medicaid enrollment requirements; potential reductions in marketplace premium tax credits, which helped more than double plan enrollment after they were made more generous in 2021; and recent regulatory and proposed legislative changes that will eliminate marketplace eligibility for many people and make it much harder for those who need health insurance to enroll in marketplace plans and keep their coverage over time."

Sara Heath has reported news related to patient engagement and health equity since 2015.

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