Gas prices hit $4 a gallon in District Prices hit $4 for a gallon of regular gasoline in the District on Thursday, only the fifth time pump prices have ever crossed that threshold in the nation's capital, the mid-Atlantic AAA said. The price jumped 4 cents a gallon from the day before. Nationwide, the price of a gallon of regular gasoline climbed to $3.78 a gallon, up 47 cents in the past month, the AAA said. The Energy Information Administration issued a report Thursday saying about two-thirds of the gasoline price increase since the start of the year was due to higher refinery margins. It said the difference between the price of a barrel of crude oil and the price of a barrel of refined products had widened since Jan. 1. The report said wholesale gas prices had risen even faster than retail prices and that motorists might face more increases. Despite some signs of easing, it said, gasoline prices would remain "volatile."