This rule establishes initial air quality designations for most areas in the United States, including most areas of Indian country, for the 2015 primary and secondary national ambient air quality standards (NAAQS) for ozone. In this action, the Environmental Protection Agency (EPA) is designating 2,646 counties, including Indian Country located in those counties, two separate areas of Indian Country, and five territories as Attainment/Unclassifiable and three counties as Unclassifiable.