A new study of every county in the United States finds deaths due to drug use increased more than 600 percent between 1980 and 2014. Almost 550,000 deaths were attributed to drug use over the study’s 35 years.

In some counties in Kentucky, West Virginia, Ohio, Indiana, and eastern Oklahoma, increases in drug-related deaths exceeded 5,000 percent, according to ABC News. The study did not distinguish between illegal and prescription drugs.

Death rates decreased for alcohol use disorders, self-harm, and interpersonal violence at the national level between 1980 and 2014, the researchers wrote in the Journal of the American Medical Association.

“To our knowledge, this study is the first at the county level to consider drug use disorders and distinguish between intentional and unintentional overdoses,” lead researcher Dr. Laura Dwyer-Lindgren of the Institute for Health Metrics and Evaluation said in a news release.