North American Free Trade Agreement Implementation Act, Pub. L. No. 103-182, 107 Stat. 2057 (1993); 19 U.S.C. 3301 et seq. and other sections listed in the "Short Title" note and in the U.S.C.A. Tables under Pub. L. No. 103-182. Treaties in Force...January 1, 2010 does not give any T.I.A.S. or U.S.T. citation for the NAFTA.
Exec. Order No. 12,889 (Dec. 27, 1993), implementing the NAFTA
For more information about some of these, see U.S. government websites, etc., WTO/GATT Research Guide.