The U.S. Commerce Department released the trade data on Thursday. The U.S. trade deficit widened to $46.56 billion in December from a deficit of $39.75 billion in November. That was the lowest level since November 2012.
November's figure was revised down from a deficit of $39.0 billion.
Analysts had expected a trade deficit of $38.0 billion.
The decline of a deficit was driven by falling oil prices, a stronger greenback and a strengthening U.S. economy.
Exports decreased 0.8% in December, while imports rose 2.2%.