An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

General Conformity

Transportation Conformity Regulations and the General Conformity Regulations

In November 1993, EPA promulgated two sets of regulations to implement Section 176(c) of the Clean Air Act. First, on November 24, EPA promulgated the Transportation Conformity Regulations, which apply to highways and mass transit. These regulations establish the criteria and procedures for determining whether transportation plans, programs, and projects funded under title 23 U.S. C. or the Federal Transit Act conform with the State Implementation Plan (SIP) (58 FR 62188).

Then, on November 30, EPA promulgated a second set of regulations, known as the General Conformity Regulations, which apply to all other federal actions. These regulations ensured that other federal actions also conformed to the SIPs (58 FR 63214).

Final revisions to the General Conformity Regulations were published March 24, 2010.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.