The increasing levels of atmospheric greenhouse gases (GHGs) caused by the increased use of fossil fuels for energy services, including transport, heating and electricity production, are known to be one of the main drivers of climate change. The United States is responsible for a quarter of the world's total greenhouse gas emissions, representing only 5% of the world's population, and it becomes the world's largest emitter of atmospheric greenhouse gases (EPA, 2011). Since 1970, the United States' share of net crude oil imports and consumption has increased significantly and the majority of imported liquid petroleum fuels have been used for the US transportation sector (EIA, 2010). Today, transportation is the second largest source of final energy sector emissions (CO2), after the electric power sector in the United States. In 2008, the U.S. transportation sector became the largest contributor to CO2 emissions, accounting for 95 percent of CO2 emissions. GHG emissions from the transportation sector in the United States represent one-third of total U.S. GHG emissions (EPA, 2011). In the same year, the U.S. light transportation sector, including passenger cars and light trucks, consumed approximately 60% of the total supply of liquid petroleum fuels (EIA, 2010). Due to the carbon-intensive fossil fuel supply, GHG emissions from light-duty vehicles accounted for approximately 40% of total GHG emissions from the transportation sector in the United States (EIA, 2010). Over the coming decades, the demand and consumption of liquid petroleum fuels needed for light transportation is expected to grow rapidly (EIA, 2010). Due to the increase in gasoline consumption for internal engine combustion, there could be an increase in G...... middle of paper ......p://www.fueleconomy. gov/feg/noframes/31016.shtmlUNEP. (2009). Hybrid electric vehicles: an overview of current technology and its applications in developing and transition countries. Nairobi, Kenya: United Nations Environment Program. US DOT. (2003, October). OmniStats - In a typical day, how many miles do you travel one way between home and work? Retrieved October 12, 2011 from Research and Innovative Technology Administration (RITA): http://www.bts.gov/publications/omnistats/volume_03_issue_04/html/figure_02.htmlUS OPM. (2011). Federal Holidays 2011. Retrieved October 1, 2011 from the US Office of Personnel Management: http://www.opm.gov/operating_status_schedules/fedhol/2011.aspWeisser, D. (2007). A guide to greenhouse gas (GHG) emissions from electricity supply throughout the life cycle. Austria: Planning and Economic Studies Section, International Atomic Energy Agency.