This document discusses strategies to reduce transportation sector emissions in the United States. It notes that transportation accounts for 27% of total US emissions and over half of emissions from passenger vehicles. The document outlines strategies to improve vehicle efficiency through increased fuel economy standards and use of low-carbon fuels. It also discusses opportunities to improve system efficiency through better transportation, land use, and infrastructure planning. These strategies could reduce transportation emissions by 17-38% by 2020 and up to 80% by 2050 according to analysis by the Natural Resources Defense Council.