In this final action, the EPA is amending its reformulated gasoline (RFG) regulations to reflect the reclassification of several ozone nonattainment areas as Severe for the 2008 ozone national ambient air quality standard (NAAQS). The subject areas are the Dallas-Fort Worth, TX area (Dallas), the Denver-Boulder-Greeley-Fort Collins-Loveland, CO area (Denver), and the Eastern Kern County, CA area (Eastern Kern). The reclassification of the Dallas and Denver areas as Severe for the 2008 ozone NAAQS was effective on November 7, 2022, and results in the prohibition of the sale of conventional gasoline throughout the entire nonattainment area under the Clean Air Act (CAA) on 7 November 2023. Similarly, the reclassification of the Eastern Kern area was effective on 7 July 2021, and the Federal RFG requirement applied to the area on 7 July 2022. This final rule is effective 13 November 2023. POC is Mark Coryell, Office of Transportation and Air Quality, EPA, 2000 Traverwood, Ann Arbor, MI 48105; email: coryell.mark@epa.gov. (Federal Register 12 October 2023 [Rule] Pages 70602-70605)