Pursuant to the Federal Clean Air Act (CAA or the Act), the Environmental Protection Agency (EPA or the Agency) is finalizing the disapproval of State Implementation Plan (SIP) submissions for 19 states regarding interstate transport and finalizing a partial approval and partial disapproval of elements of the SIP submission for two states for the 2015 8-hour ozone national ambient air quality standards (NAAQS). The "good neighbor" or "interstate transport" provision requires that each state's SIP contain adequate provisions to prohibit emissions from within the state from significantly contributing to nonattainment or interfering with maintenance of the NAAQS in other states. This requirement is part of the broader set of "infrastructure" requirements, which are designed to ensure that the structural components of each state's air quality management program are adequate to meet the state's responsibilities under the CAA. Disapproving a SIP submission establishes a 2-year deadline for the EPA to promulgate Federal Implementation Plans (FIPs) to address the relevant requirements, unless the EPA approves a subsequent SIP submission that meets these requirements. Disapproval does not start a mandatory sanctions clock. The EPA is deferring final action at this time on the disapprovals it proposed for Tennessee and Wyoming.