The Environmental Protection Agency (EPA) is approving a State Implementation Plan (SIP) revision submitted by the North Carolina Department of Environmental Quality, Division of Air Quality (DAQ), through a letter dated March 21, 2018, readopting and amending air quality rules related to transportation conformity requirements in the state of North Carolina. EPA has determined that North Carolina's March 21, 2018, SIP revision is consistent with the federal transportation conformity requirements and the Clean Air Act (CAA or Act).