Texas still has the highest rate of people lacking health insurance in the country, but overall, rates in the state and across the nation have been on the decline, new Census data show.

The number of uninsured Americans dropped 8.8 percent nationwide during the last year of the Obama administration, and that could further complicate continued Republican efforts to dismantle the Affordable Care Act.

At 16.6 percent, about one in every six Lone Star State residents did not have health coverage in 2016, the American Community Survey data released Tuesday found. Texas and Alaska were the only two states that had rates that were over 14 percent of their populations.

It's a troubling statistic, especially when compared to Massachusetts, which had the nation’s lowest rate of uninsured nationally: About 2.5 percent, or one out of every 40 people there, were uninsured last year.

Still, Texas was one of 39 states that saw improvements between 2015 and 2016, though by slightly narrower margins than in previous years.

Texas experienced year-over-year declines in uninsured, despite the state’s refusal to expand Medicaid. An Affordable Care Act provision available since 2014 allowed states to expand the number of low-income families that qualified for the federal program.

In 2013, 5.7 million Texans were uninsured. That number dropped to 4.5 million in 2016. Drops in uninsured rates were greater in states that did expand enrollment for the Medicaid program.

Looking forward, health policy analysts worry that progress could stall or revert in coming years, given the still-uncertain future of the Obama-era health care law.

Republican attempts to repeal or replace the Affordable Care Act have floundered over the past few months, and the effort has left a ton of uncertainty that could have an immediate impact on 2018 open enrollment, which is scheduled to run from Nov. 1 to Dec. 15 this year.

Last month, the Centers for Medicare & Medicaid Services also slashed the advertising budget to promote enrollment into the federally facilitated and state-based marketplaces. The budget for navigators, the people who help educate consumers about their enrollment options, was also cut.