When President Obama signed the Affordable Care Act (ACA) into law, advocates hailed it as the most important health legislation since the creation of Medicaid and Medicare in 1965, and one of the most important anti-poverty laws in decades as well. The monumental nature of the ACA has become more evident every year since its implementation, and it’s time to take a moment to celebrate the success. New data from the U.S. Census Bureau confirms that there’s a lot to celebrate, but also reminds us that there’s a lot of work yet to be done. Nationally, from 2013 to 2014, the first year the ACA was fully implemented, the uninsurance rate dropped by 2.9 percentage points, the largest single year drop on record. Every single state saw a decrease in the rate of uninsurance. That is a big cause for celebration!

Yet with the good news also comes a reminder of how much work remains to realize the full vision of the ACA and address the disparate access to health insurance that the poorest Americans face. A key element of the ACA was to provide health insurance through Medicaid to individuals and families with incomes up to 138 percent of poverty. When the Supreme Court ruled in 2012 that states could opt out of expanding Medicaid, it created a reality where geography determines which of our poorest citizens have access to health care. Census data confirms that the states that have not yet chosen to expand Medicaid experienced smaller declines in uninsurance.

Those living below 100 percent of poverty ($19,790 for a family of three in 2014) have the highest rate of uninsurance – 19.3 percent. This reinforces that many who Congress intended to be insured through the expansion of Medicaid have instead fallen into a coverage gap, which was created by their state’s decision to not expand Medicaid combined with their being ineligible for tax credits to purchase subsidized coverage The coverage gap affects those in non-expansion states under 100% of poverty who are not eligible for Medicaid under their state’s existing income eligibility limits and who don’t make enough to receive subsidies to purchase health insurance through the ACA marketplace. In many states, adults without dependent children are not eligible at all for Medicaid, no matter how poor they are, and parents are only eligible at very low income levels. An Urban Institute report found that 22.6 percent of the uninsured fell into this coverage gap. Other reasons why people remain uninsured include being unaware of financial assistance or having the perception that health insurance is unaffordable, even when financial assistance is available.

It’s important to pause and celebrate the successes of the ACA for all the ways it has increased access to health insurance. The ACA is here to stay, but there is a lot of work left to make sure its full potential is realized. That’s why advocates in non-expansion states continue to work hard toward Medicaid expansion, which will give us even more reasons to celebrate with each new state that expands.