Most of the cost of oil can be attributed to exploration, drilling and pumping.
Americans are saving a buck a gallon on gas, giving them much greater spending power.
Basically, anywhere and everywhere it can be stored.
Too much oil means prices fall, but also oil companies cutting back.
Poorer people spend much more of their income on commuting.
There's an oil and gas boom in North America thanks to an innovation known as hydraulic fracturing that extracts natural gas and oil from shale rock deep underground. Here's how it works.
