than $1 out of every $10 produced in the U.S. gross domestic product is related to transportation activity. This includes all aspects of transportation, including the movement of goods and the purchase of all transportation-related products and services as well as the movement of people". Employment in the transportation and material moving industry accounted for 7.4% of all employment, and was the 5th largest employment group in the United States. The United States invests 0.6% of its GDP on transportation annually. Environmental impacts Two-thirds of U.S. oil consumption is due to the transportation sector. The "Energy Independence and Security Act of 2007" has a significant impact on U.S. Energy Policy. The United States—an important export country for food stocks—will convert 18% of its grain output to ethanol in 2008. Across the United States, 25% of the whole corn crop went to ethanol in 2007. The percentage of corn going to biofuel is expected to go up. In 2006, U.S. Senators introduced the BioFuels Security Act, which would mandate the production of dual-fuel vehicles and the sale of E85 ethanol fuel. In 2016 transportation became the leading source of greenhouse gas emissions (28.5%), exceeding electricity generation (28.4%). See also United States Department of Transportation Transportation in Canada List of U.S. cities with high transit ridership List of countries by vehicles per capita American Public Transportation Association History of rail transport in the United States Plug-in electric vehicles in the United States Road signs in the United States Timeline of United States railway history Transportation safety in the United States Timeline of transportation technology Location-specific Transportation in Atlanta Transportation in Boston Transportation in Buffalo, New York Transportation in Charlotte, North Carolina Transportation in Chicago Transportation in Cincinnati Transportation in Dallas Transportation in Los Angeles Transportation in St. Louis Transportation in Guam Transportation in Hampton Roads Transportation in Houston Transportation in Indianapolis Transportation in the Inland Empire Transportation in Las Vegas Transportation on Long Island Transportation in Louisville, Kentucky Transportation in Memphis, Tennessee Transportation in metropolitan Detroit Transportation in Miami Transportation in New England Transportation in New York City Transportation in Norfolk, Virginia Transportation in Omaha Transportation in Pittsburgh Transportation in Portland, Oregon Transportation in Philadelphia Transportation in Puerto Rico Transportation in Richmond, Virginia Transportation in the Sacramento metropolitan area Transportation in Salt Lake City Transportation in San Diego Transportation in the San Francisco Bay Area Transportation in Seattle Transportation in the United