In accordance with section 126 of the Clean Air Act (CAA), EPA is taking final action on petitions filed by eight Northeastern States seeking to mitigate what they describe as significant transport of one of the main precursors of ground-level ozone, nitrogen oxides (NO<INF>X</INF>), across State boundaries. Each petition specifically requests that EPA make a finding that NO<INF>X</INF> emissions from certain stationary sources emit in violation of the CAA's prohibition on emissions that significantly contribute to ozone nonattainment problems in the petitioning State. If EPA makes such a finding, EPA is authorized to establish Federal emissions limits for the sources. The eight Northeastern States that filed petitions are Connecticut, Maine, Massachusetts, New Hampshire, New York, Pennsylvania, Rhode Island, and Vermont. Today, EPA is making final determinations that portions of six of the petitions are technically meritorious. The technically approvable portions of the petitions will be automatically deemed granted or denied at certain later dates pending certain actions by the States and EPA regarding State submittals in response to the final NO<INF>X</INF> State implementation plan call (NO<INF>X</INF> SIP call). This rule describes the schedule and conditions under which applicable final findings on the petitions would be automatically triggered. The EPA intends to implement the section 126 control remedy through a Federal NO<INF>X</INF> Budget Trading Program. The trading program would apply to sources in the source categories for which a final finding is ultimately granted. In today's rule, EPA is finalizing the general parameters of the trading program. The EPA is committing to promulgate the details of the trading program by July 15, 1999. The EPA is including interim final emissions limitations for affected sources which would apply only if EPA fails to promulgate the trading program prior to a section 126 finding. Mitigation of the transport of ozone and