Deprivation, isolation and lack of access to mental health care all appear to be driving the crisis in rural America, said lead researcher Danielle Steelesmith. She's a postdoctoral fellow at Ohio State University's Wexner Medical Center in Columbus.
"Rural suicide rates are higher than urban rates and tend to be increasing a little more rapidly," Steelesmith said.
Suicide rates increased 41% between 1999 and 2016, from a median of 15 per 100,000 people to more than 21 per 100,000, county-by-county data show. Median means half had higher rates; half were lower.
Rural folks tend to be at higher risk than city dwellers, the researchers found.
Suicide rates were 22 per 100,000 in rural counties between 2014 and 2016, compared with about 18 per 100,000 in large metropolitan counties, the nationwide data revealed.
To figure out the difference between rural and urban areas, the researchers did a county-by-county analysis of factors that could be driving suicide rates.
"Deprivation" - a cluster of factors that includes low employment, poverty and lack of education - was closely related to increased rural suicide rates, the study authors said.
Steelesmith said poverty could be more entrenched and economic opportunities more limited in rural areas, leaving residents feeling helpless.
Mayo Clinic psychiatrist Dr. J. Michael Bostwick noted that the highest suicide rates found in the study occurred in the Mountain West, Appalachia and the Ozarks.
"The communities that are more likely to be suffering rurally are the ones that are still committed to mining or farming," Bostwick said. "Information technology, alternative energy and automation may have bypassed rural communities in favor of metropolitan communities."
Residents of rural America also appear to be more isolated, which increases suicide risk, the researchers noted.
And rural regions tend to have more social fragmentation, with more single-member households, unmarried residents and people drifting in and out of the area, according to the report.
These regions also have lower levels of social capital, a measure of the interconnectedness of people through churches, groups and organizations, Steelesmith said.
Both social fragmentation and lack of social capital were associated with higher suicide rates, the findings showed.
Rural residents struggling with depression or suicidal thoughts also are less able to get help, either because they aren't insured or the area lacks mental health professionals.
These people face a "double whammy" of few therapists around, along with a lack of solid suicide-prevention training in the mental health professionals who are available, said Mitch Prinstein, a professor of psychology and neuroscience at the University of North Carolina at Chapel Hill.
"If you actually do get lucky enough to get in the office of a trained mental health provider, they aren't necessarily going to be trained in effective approaches for reducing suicide," he said. "Right now, mental health treatment is much more available for folks in urban and suburban areas. It's almost impossible to access in our most rural areas of the country."
Expanding access to mental health services, possibly through telemedicine, could help reduce suicide rates in rural areas, Steelesmith suggested.
One factor that drove urban suicide rates but not rural was the number of gun shops in an area.
Firearms shops increase access to guns and make suicide more viable to troubled people, Bostwick said.
"Rural areas are saturated with firearms already, so gun shops don't make a difference," he said. "But when you open a gun shop in a part of a city that doesn't have one, access is increased and rates go up."
Prinstein and Bostwick differ in how they see America's rising suicide rates.
"We really need to start talking about suicide like the public health crisis that it is, the same way we talk about flu shots in every drug store, and we talk about sexual risk being discussed in every school and community health clinic," Prinstein said. "When the percentages are this high, this needs to be something that's part of the public discourse in the same way we talk about sex and drugs."
But Bostwick noted that rates are actually relatively low, with 21 suicides for every 100,000 people.
"I don't mean to minimize the significance of any individual suicide, but it is still a pretty rare event," he said.
Bostwick added that today's suicide rates are similar to those in the early 1990s, and appear to be part of an up-and-down cycle taking place in the United States for at least the past century.
The new study was published online Sept. 6 in JAMA Network Open.