A cap-and-trade program meant to help control nitrogen oxide emissions, to achieve additional reductions during the ozone season in parts of the United States. Established by the Ozone Transport Commission, the program calls for an ozone season NOx budget, which caps emissions from May 1 to September 30, for each of the twenty-one affected states and the District of Columbia. The unique feature of this program is its focus on seasonal emissions. Whereas most emissions trading programs focus on reducing annual emissions, this program, recognizing the important seasonal component in the formation of ozone in the Northeast, focuses only on those emissions that will directly contribute to the problem.