NEW YORK — Oil slid today to its lowest price in a month as investors started to pay more attention to a yearlong slump in American energy demand.

For most of the year, oil prices surged as investors pumped money into crude contracts to protect themselves from a weakening dollar. Oil was thought of as a safe bet with demand expected to rise next year, and crude prices doubled from March to October.

But as the recession wore on, consumers and businesses continued to use less gasoline, diesel and other petroleum products than a year ago. Refiners struggled.

Energy Information Administration data showed this week that refiners are operating at the lowest levels ever — except for years when hurricanes disrupted operations in the Gulf of Mexico — according to analyst Stephen Schork.

Benchmark crude for December delivery lost 44 cents at $76.50 a barrel on the New York Mercantile Exchange. Prices dipped as low as $75.57 earlier in the day, the cheapest since Oct. 15.