For the first time in a decade, the number of Americans without health insurance has risen — by about 2 million people in 2018 — according to the annual U.S. Census Bureau report released Tuesday.

The Census found that 8.5% of the U.S. population went without medical insurance for all of 2018, up from 7.9% in 2017. By contrast, in 2013, before the Affordable Care Act took full effect, 13.3% were uninsured. It was the first year-to-year increase since 2008-09, Census officials said.

Census officials said most of drop in health coverage was related to a 0.7% decline in Medicaid participants. The number of people with private insurance remained steady and there was a 0.4% increase in those on Medicare.

Many of those losing coverage were non-citizens, a possible fallout from the Trump administration’s tough immigration policies and rhetoric. About 574,000 non-citizens lost coverage in 2018, a drop of about 2.3%, the report found.

“Uninsured non-citizens account for almost a third of the increase in uninsured, which may reflect the administration’s more aggressive stance on immigration,” said Joseph Antos, a health economist at the American Enterprise Institute.

The increase in the number of uninsured people in 2018 was remarkable because uninsured rates typically fall or hold steady when unemployment rates drop. The U.S. unemployment rate fell slightly from about 4.3% in 2017 to 4% in 2018.

The uninsured rate continued to vary by poverty status and whether a state expanded its Medicaid program under Obamacare. Texas (17.7%), Oklahoma (14.2%), Georgia (13.7%) and Florida (13%) had the highest uninsured rates in 2018, according to the report. None of those states have expanded Medicaid under Obamacare.

The percentage of uninsured children under the age of 19 increased by 0.6 percentage points from 2017 to 2018, to 5.5%.

“The Census data are clear — the uninsured rate for kids is up sharply and it’s due to a loss of public coverage — mostly Medicaid,” Joan Alker, executive director of Georgetown University Center for Children and Families, said in a statement.

“These children are not getting private coverage as the Trump Administration has suggested but rather becoming uninsured,” she said. “This serious erosion of children’s health coverage is due in large part to the Trump Administration’s actions that have made health care harder to access and have deterred families from enrolling their children.”

The share of Americans without medical insurance fell steadily since 2014 but then leveled off in 2017, the year Donald Trump became president.

Health care advocates have complained that efforts by the Trump administration and Congress are jeopardizing insurance enrollment. They point to cuts in outreach programs that aim to tell consumers about their health care options under Obamacare and the elimination of the ACA’s tax penalty for people who don’t have health coverage.

Alker complained that the administration’s policies are causing the loss of children’s coverage. “In a period of continued economic and job growth, we shouldn’t be going backwards on health coverage,” said Judy Solomon, a senior fellow for the Center on Budget and Policy Priorities, a left-leaning think tank. “This backsliding almost certainly reflects, at least in part, Trump administration policies to weaken public health coverage.”

She attributed the drop to the Trump administration making it harder for families to enroll for coverage in Medicaid by curtailing outreach efforts, allowing states to ask for more paperwork and proposing a so-called public charge rule that would make it harder for legal immigrants to get permanent resident status if they have received certain kinds of public assistance — including Medicaid.

Tom Miller, a resident fellow at the American Enterprise Institute, a conservative think tank, said the drop in Medicaid coverage “is a positive.”

“When the economy grows Medicaid eventually drops,” he said.

One reason for the drop in health coverage is that middle-income families can’t afford the rising cost of insurance in the individual market, particularly if they don’t qualify for government subsidies, he added.

“On balance, this is some short-term noise,” he said of the uptick in the uninsured rate. “I would put more stake in it if happens for several years.”

Chris Pope, a senior fellow with the conservative Manhattan Institute, also said he considered the change “fairly small” and likely due to increasing wages “pushing people above the income eligibility cutoff in Medicaid expansion states.”

But he suggested that next year would be a better indicator of how changes in the ACA are playing out.

“I expect that the mandate repeal will make next year’s increase in the uninsured more significant,” he said.