This Healthcare Cost and Utilization Project (HCUP) Statistical Brief presents characteristics of U.S. counties based on population rates of opioid-related inpatient stays and treat-and-release ED visits for patients aged 15 years and older using comprehensive information from the 2016 State Inpatient Databases (SID) and State Emergency Department Databases (SEDD) from 35 States and the District of Columbia. County was defined based on patient ZIP Code of residence.