An oil pump jack in a Central California field. Increased domestic production is one factor behind the decline in oil prices.Credit…Alisha Jucevic for The New York Times When Russia invaded Ukraine last spring, energy experts were predicting that oil prices could reach $200 a barrel, a price that would send the costs of shipping and transportation into the stratosphere and bring the global economy to its knees. Now oil prices are lower than they were when the war began, having dropped more than 30 percent in barely two months. On Monday, news of a slowing Chinese economy and a cut in Chinese interest rates sent prices down further, to less than $90 a barrel for the American benchmark. Gasoline prices have fallen every day over the last nine weeks, to an average of less than $4 nationwide, and prices of jet fuel and diesel are easing as well. That […]