WASHINGTON — The United States trade deficit fell in November to the lowest level in 11 months as crude oil imports dropped to a two-decade low.

The trade deficit narrowed to $39 billion in November, down 7.7 percent from a revised October deficit of $42.2 billion, the Commerce Department said on Wednesday. United States exports slipped 1 percent to $196.4 billion as sales of commercial airliners fell.

Imports dropped even faster, falling 2.2 percent to $235.4 billion, which was primarily a reflection of foreign oil declines. The volume of crude oil imported in November hit its lowest level since 1994, while the average price dropped to a two-year low.

The United States trade deficit is being helped by falling global oil prices and a boom in American energy production, which has decreased the country’s reliance on imports.