Editors' Summary: In Air Pollution Control District of Jefferson County v. United States Environmental Protection Agency, the Sixth Circuit upheld EPA's refusal to tighten the Indiana sulfur dioxide (SO₂) control requirements on an Indiana power plant that pollutes the air of Jefferson County, Kentucky from a mile across the state border. The court ruled that EPA properly processed, and then rejected, the county's Clean Air Act §126 petition for a revision in the Indiana requirements. The author reviews the case and discusses the Act's failure to respond to interstate inequity in pollution control burdens. Four power plants contaminate the air of Jefferson County. The three in Kentucky have had to install expensive scrubbers to limit their emissions to 1.2 pounds per million Btus of heat input, the one in Indiana, only a few miles away, has a standard six times as high that allows it to burn cheap high-sulfur coal without controls. The decision demonstrates that the interstate pollution provisions as currently interpreted by EPA do not address this issue. Coupled with earlier decisions rejecting charges that relaxations of SO2 emission standards in some states contribute to sulfate particulate pollution in others (and perhaps to acid rain), Jefferson County consigns the interstate pollution control provisions of the Clean Air Act to very limited roles.