The Environmental Protection Agency (EPA) is determining that the Las Vegas, Nevada area failed to attain the 2015 ozone national ambient air quality standards (NAAQS or "standards") by the applicable attainment date. The effect of failing to attain by the applicable attainment date is that the area will be reclassified by operation of law from "Moderate" to "Serious" nonattainment for the 2015 ozone NAAQS on January 21, 2025, the effective date of this final rule. This action fulfills the EPA's obligation under the Clean Air Act (CAA) to determine whether the Las Vegas, Nevada ozone nonattainment area attained the NAAQS by the attainment date and to publish a document in the Federal Register identifying the area as having failed to attain and identifying the reclassification.