cars

According to a 2012 report from the Congressional Research Service, “U.S. Energy: Overview and Key Statistics,” petroleum accounts for 40% of all U.S. energy consumption. As of 2010, petroleum was predominantly used for transportation (70.5%), followed by industrial (22.9%), residential (5.7%) and electricity generation (0.9%) uses.

At the beginning of 2015 the average price of a gallon of gasoline in the United States stood at about $2.20, approximately $1.10 less than it had been a year earlier. In markets such as the Gulf Coast and the Midwest, it had fallen below $2 a gallon.

Car emissions account for half of the carbon monoxide pollution in the United States, one third of the nitrogen oxide pollution, and 10% of fine particulate matter emissions. Areas of heavy traffic congestion — which see concentrated emissions levels in the ambient air — are of particular concern, as previous research has linked such pollution with negative effects on fetal health.

Once upon a time, the American family of the popular imagination lived in the suburbs, had 2.5 children, and spent its weekends washing the car in the driveway. The United States has become increasingly diverse and significantly more urban over time, however, and such images no longer hold true for much of the country — even to the exclusion of that most American of icons, the family car.