In today's action, EPA is revising the compliance date and other related dates for sources subject to a final rule published on January 18, 2000, known as the Section 126 Rule. The EPA promulgated the rule in response to petitions submitted by four Northeastern States under section 126 of the Clean Air Act (CAA) for the purpose of mitigating interstate transport of nitrogen oxides (NO<INF>X</INF>) and ozone. Nitrogen oxides are one of the main precursors of ground-level ozone pollution. The Section 126 Rule requires electric generating units (EGUs) and non-electric generating units (non-EGUs) located in 12 States and the District of Columbia to reduce their NO<INF>X</INF> emissions through a NO<INF>X</INF> cap-and-trade program. Originally, EPA harmonized the Section 126 Rule with a related ozone transport rule, known as the NO<INF>X</INF> State implementation plan call (NO<INF>X</INF> SIP Call), by establishing the same compliance date, May 1, 2003. A court action subsequently delayed the NO<INF>X</INF> SIP Call compliance deadline until May 31, 2004. More recently, on August 24, 2001, the court temporarily tolled (suspended) the Section 126 Rule compliance date for EGUs pending EPA's resolution of an issue remanded by the court related to EGU growth factors. On April 23, 2002, EPA issued its response to the growth factor remand. That action reactivated the compliance period for EGUs after nearly a year delay. Therefore, with this final rule, EPA is resetting the EGU compliance date and other related dates, such as the monitoring certification date. The EPA is also resetting the dates for non-EGU sources to match the new dates for EGUs. The new compliance date is May 31, 2004. In general, other related dates are extended by one year from the original deadlines. Today's rule once again aligns the Section 126 Rule with the NO<INF>X</INF> SIP Call.