Death rates in the US hit a historic low in 2014, but they’re dropping much more slowly outside of the big metropolitan areas, new science says. This disparity reveals a massive health gap between rural and urban populations. The 46 million people who live in rural areas need better access to affordable medical care, and public health programs that promote healthy habits, CDC scientists say.

A higher percentage of people under age 80 who live in rural regions die of heart disease, cancer, lung disease, stroke, and accidental injuries, according to results published today by the Centers for Disease Control and Prevention. What’s more, the researchers estimated that more of the deaths from accidental injuries and lung disease were preventable in rural regions than in metropolitan areas.

In the study, epidemiologists compared death rates and causes of death for each group between 1999 and 2014, and calculated how many deaths were what the CDC considers preventable.

The authors of a commentary published alongside the research paper attributed the higher rural death rates to demographics: people who live in rural areas “tend to be older, poorer, and sicker than their urban counterparts,” they wrote. More people smoke, fewer people eat healthy diets, and fewer people are able to exercise in their spare time — in large part because many suffer from chronic health conditions, according to the report. Illness and poverty make it even more difficult, if not impossible, to take the time to cook healthy food or go for a run, which can make sick people sicker.

All of these risk factors contribute to higher rates of high blood pressure and obesity, which themselves are risk factors for cardiovascular disease, cancer, and stroke. Because there are more underinsured and uninsured people living in rural regions than in cities, people also have less access to preventative care like cancer screenings — which means that a dangerous health problem could easily be missed until it’s too late.

Deaths from accidental injuries are almost 50 percent more common in rural areas. That includes more opioid overdoses, possibly because of unsafe prescribing practices as well as  restrictions on who can administer an antidote to overdoses called naloxone. Car crashes are also more lethal, at least in part because fewer people wear seat belts, according to the report. Trauma centers with the resources and expertise to treat devastating injuries are much farther away — which means injured people are more likely to die without the care they need.

Curbing the higher death rate in rural areas will take increasing access to care, as well as education, according to the CDC’s commentary. But as the government discusses repealing the Affordable Care Act, which gave 20 million uninsured people health insurance, it could be even harder for people to get the care they need in the future.