The EPA is approving the Texas Mass Emissions Cap and Trade (MECT) program as a revision to the Texas State Implementation Plan (SIP). The program was submitted on December 22, 2000. The MECT program will contribute to attainment of the 1-hour ozone National Ambient Air Quality Standard (NAAQS) in the HGA ozone nonattainment area. The EPA is approving these revisions to the Texas SIP to regulate emissions of NO<INF>X</INF> in accordance with the requirements of the Federal Clean Air Act (the Act). The EPA proposed approval of the Texas MECT program on July 23, 2001 on the condition that Texas resolve eight issues. The State revised the MECT rule to adequately address the EPA issues identified in the proposed rulemaking and submitted these revisions to EPA as a SIP revision which EPA is approving in this action by parallel processing. Comments were received on the proposed rulemaking from Environmental Defense, Inc. on September 22, 2001, from Baker and Botts L.L.P. representing the Business Coalition for Clean Air Appeal Group on August 13, 2001, and from Reliant Energy, Inc. on August 13, 2001. The major comments regarded the use of credits from other trading programs for MECT compliance, inflation of the cap, undermining of the attainment demonstration, emissions monitoring and program evaluations. After reviewing the comments and the State response to the eight issues raised in the proposed rulemaking, EPA has concluded that the Texas MECT program fully satisfies all relevant guidance and the Clean Air Act.