Given America's new oil rush, it would seem the best of times for gas prices. But with $4-per-gallon sticker shock, it might feel like the worst of times. How can this be? The question is all the more perplexing, because the United States is not only producing more crude oil but also using less of it. As a result, net oil imports have dropped a third since 2005. With such good fortune, America's soaring pump prices seem to defy the laws of supply and demand — except for one fact: It's increasingly not just about us. U.S. gas prices are largely determined by global crude oil prices, which depend on a widening and shifting array of factors half a world away: economic sanctions on Iran; deepwater drilling off Brazil; spare oil capacity in Saudi Arabia; auto use in China; less nuclear power in Japan. So oil rigs may be hopping in North Dakota, but what happens in the Strait of Hormuz will likely have more impact on prices at the local gas station — even though th...