We have an unhealthy dependency on 19 million barrels per day of liquefied plant and animal matter from the Mesozoic era. That works out to almost three gallons every day for every man, woman, and child in the country. Remember the harrowing footage of oil spewing out of BP's Gulf well? The United States uses more than four times the amount of the spill in one day.
The easy portability of oil's explosive energy has made us the most mobile humans in history. Fears of peak oil notwithstanding, it is also still very cheap. The gallon of gas that was $2.30 in real dollars in 1960 cost only $2.73 in 2010. No surprise, then, that petroleum powers 95 percent of all transportation in the United States.
The Sierra Club's Beyond Oil campaign proposes to move the United States off oil in the next 20 years. An article on the Club's Web site sketches out how it can be done.