The Environmental Protection Agency (EPA) is correcting errors in the regulatory text regarding the designation of certain areas in nine states for the 2015 ozone national ambient air quality standards (NAAQS). The designation rules were signed by the EPA Administrator on November 6, 2017, and April 30, 2018. The errors include typographical and formatting errors and the omission from the regulatory tables of several counties designated as attainment/unclassifiable. The EPA is correcting the errors consistent with the rulemaking record. The affected areas are located in California, Illinois, Indiana, Kentucky, Michigan, Montana, Ohio, Pennsylvania and Virginia.