When congressional candidates last hit the campaign trail in 2014, one word seemed to be at the top of the agenda for virtually every Republican: Obamacare. But that was before most of the law’s provisions took effect. Two years later, the health law seems to have faded as a campaign issue.

New data released this month might give a hint as to why: The uninsured rate — the share of the population without health insurance — dropped in every congressional district in the country between 2013 and 2015, according to the American Community Survey.

Obamacare’s troubles are far from over. Recent months have brought a spate of headlines about big insurers pulling out of the law’s health insurance marketplaces, and (somewhat misleadingly) about soaring insurance premiums. The law, formally known as the Affordable Care Act, remains as polarizing as ever: Two-thirds of Democrats say they have a favorable view of the law, and 76 percent of Republicans view it unfavorably, according to an August poll from the Kaiser Family Foundation, which researches health care policy.

But on one metric, at least, the law seems to be working: More people are getting coverage. According to other Census Bureau data released last week, 4 million people gained insurance last year. About 29 million Americans still don’t have insurance, 13 million fewer than before the law took effect.

The biggest improvements in the uninsured rate came in California, a state that fervently embraced the controversial law. About a third of the state’s residents are now enrolled in California’s Medicaid program, and 1.38 million people are enrolled in private insurance through the state’s health insurance marketplace after a multimillion-dollar campaign to promote it. (Check out the table at the end of this article to see how uninsured rates changed in every district.)

At the other end of the spectrum, the smallest declines in the rate of uninsured were mostly in Massachusetts, which passed a law in 2006 requiring residents to have insurance. (The Massachusetts law was a model for the ACA.) The state already had high rates of coverage as a result. For example, in District 8, which had the highest rate of coverage of any congressional district in 2015, coverage only increased by 1.5 percentage points from the previous year

There are some exceptions at the top and bottom of the list, however, and several interesting nuggets in between:

From 2013 to 2015, about 80,000 people gained insurance in Kentucky’s District 5, an area that’s rural, relatively poor and 97 percent white, causing an 11.4 percent decrease in the district’s uninsured rate. Much has been written about Kentucky’s efforts to enroll residents in health insurance during the past few years. That was under Democratic Gov. Steve Beshear, however. When Gov. Matt Bevin took office at the beginning of this year, he began making changes to the state’s Medicaid program and health insurance marketplace, which has the law’s proponents fearful that the number of uninsured could rise again.

Approximately 7,400 people gained insurance in South Dakota between 2013 and 2015, and 10,000 people in Wyoming, just a 1.1 percent and 1.9 percent improvement in the rate of coverage in each state, respectively. That’s among the lowest of any congressional district in the country (each state has only one district). Both states, in addition to North Dakota, saw no statistically significant decrease in the rate of uninsured during 2015.

California’s District 34 saw the biggest drop in its uninsured rate of any district in the country, but it still has one of the highest uninsured rates. A quarter of the district’s population was uninsured in 2015.

Even with the improvements, insurance coverage remains far from universal. Last year, we wrote about the millions of people who remained uninsured in 2014, the first year that most of the Affordable Care Act’s major provisions kicked in. The same basic patterns held in 2015: The uninsured were more likely to be Hispanics, young adults, people who haven’t graduated from high school or people with incomes below the federal poverty line who live in states that chose not to expand Medicaid.

With fewer people uninsured, the political conversation seems to be shifting to other issues such as premiums, deductibles and drug prices. Marketplace premium prices are expected to be released in the weeks leading up to the election, and though they will include steep increases for only a few select groups, the numbers are already generating broader concern.

Source: American Community Survey

Note: “AL” denotes at-large districts.