With Americans consuming 300 million gallons of gasoline every day, this really is a billion-dollar question. The answer? It's complicated. The U.S. is the world's biggest gasoline consumer, and it relies in part on imports of foreign crude oil to meet that need. Global crude supply and demand, which is influenced by politics, speculation and natural disasters, has a powerful effect on the cost of gas in America. Federal and state taxes, regulations and the cost of distribution top off prices at the pump.