Though shifts in demand and reduced production by some major producers have influenced oil prices, investor behavior is also increasing market volatility.

The Gulf of Mexico oil spill spotlights the growth of deepwater drilling and the challenges of balancing strong environmental regulation with efforts to expand U.S. domestic oil production.

Non-OPEC oil producers, which turn out most of the world’s oil, are operating near capacity.

Party caucuses, which date to the 1800s, have declined in importance but they could be decisive in choosing the 2008 Democratic presidential candidate.

Political volatility among the world’s leading oil producers suggests deeper causes for recent price spikes.