This document approves a revision to the Texas State Implementation Plan (SIP) that contains transportation conformity rules. The transportation conformity SIP revision enables the State to implement and enforce the Federal transportation conformity requirements at the State level in accordance with 40 CFR part 51, subpart T--Conformity to State or Federal Implementation Plans of Transportation Plans, Programs, and Projects Developed, Funded or Approved Under Title 23 U.S.C. or the Federal Transit Act. The final approval is limited only to 40 CFR part 51, subpart T (Transportation Conformity), and the SIP revisions submitted under 40 CFR part 51, subpart W, conformity of general Federal actions, will be addressed in a separate notice. The EPA is approving this SIP revision under section 110(k) of the Clean Air Act (CAA). The rationale for the final approval action and other information are provided in this document.