Transportation's Role in Reducing U.S. Greenhouse Gas Emissions is a report to Congress from the U.S. Department of Transportation (DOT) on the potential of transportation strategies to contribute to greenhouse gas reductions. Transportation has a significant impact on national greenhouse gas emissions, and transportation can be part of the nation's solution to the climate change challenge. The Energy Independence and Security Act (December 2007) called upon DOT, in consultation with the U.S. Environmental Protection Agency (EPA) and the U.S. Global Change Research Program (USGCRP), to conduct a study of the impact of the Nation's transportation system on climate change and strategies to mitigate the effects by reducing greenhouse gas emissions from transportation. The study is also to consider fuel savings and air pollution reduction from these measures. This report responds to that directive.