Crude oil prices dropped in New York Thursday to under $84 per barrel as U.S. inventories rose in the week. Traders expected U.S. inventories to drop. Instead, the U.S. Energy Information Administration said stockpiles rose by 4.2 million barrels in the week ending last Friday. Oil markets also take a cue from equity markets, which were jolted last week by a first-time downgrade of the United States' triple-A credit rating. Oil in early August was close to $95 per barrel. It skidded to about $80 per barrel after the downgrade, then headed higher. On the New York Mercantile Exchange, West Texas Intermediate crude oil gave up $3.74 overnight to $83.84 per barrel. Home heating oil prices lost 6.48 cents to $2.8968 per gallon. Reformulated blendstock gasoline prices shed 7.08 cents to $2.7995 per gallon. Henry Hub natural gas prices lost 3.3 cents to $3.90 per million British thermal units. At the pump, the national average price of unleaded gasoline rose slightly to $3.585 per gallon from Tuesday's $3.584, AAA said. Copyright 2011 United Press International, Inc. (UPI). Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent