The Environmental Protection Agency (EPA) is taking final action to approve portions of a revision to the South Carolina State Implementation Plan (SIP) concerning the Cross-State Air Pollution Rule (CSAPR). South Carolina submitted a draft version of this SIP revision for parallel processing on May 26, 2017, and a final version on September 5, 2017. Under CSAPR, large electricity generating units (EGUs) in South Carolina are subject to Federal Implementation Plans (FIPs) requiring the units to participate in CSAPR's federal trading program for annual emissions of nitrogen oxides (NO<INF>X</INF>) and one of CSAPR's two federal trading programs for annual emissions of sulfur dioxide (SO<INF>2</INF>). This action approves the State's regulations requiring large South Carolina EGUs to participate in new CSAPR state trading programs for annual NO<INF>X</INF> and SO<INF>2</INF> emissions integrated with the CSAPR federal trading programs and incorporates them into South Carolina's SIP, replacing the corresponding FIP requirements. These CSAPR state trading programs are substantively identical to the CSAPR federal trading programs, with the State retaining EPA's default allowance allocation methodology and EPA remaining the implementing authority for administration of the trading program. Under the CSAPR regulations, approval of these portions of the SIP revision automatically eliminates South Carolina units' obligations to participate in CSAPR's federal trading programs for annual NO<INF>X</INF> and SO<INF>2</INF> emissions under the corresponding CSAPR FIPs addressing interstate transport requirements for the 1997 Annual Fine Particulate Matter (PM<INF>2.5</INF>) national ambient air quality standards (NAAQS). Approval of these portions of the SIP revision satisfies South Carolina's good neighbor obligation for the 1997 Annual PM<INF>2.5</INF> NAAQS. EPA is not acting on any other portion of the September 5, 2017 submittal.