The US trade deficit declined by 11 percent in March to $38.8 billion due to a drop in crude oil imports, the Commerce Department said Thursday.
Imports fell overall by 2.8 percent to $223.1 billion, the largest decrease since 2009.
Exports, meanwhile, were down 0.9 percent to $184.3 billion, due to a drop in sales of machine parts, computers and farm products.
The US trade deficit ran at an annual rate of $507.7 billion in the first quarter, compared to last year's deficit of $539.5 billion.
The March deficit figure marked the second sharp drop in the US trade deficit in the past four months.
Many economists were surprised by the 11 percent decline, having forecast a slight decrease to roughly $42 billion.
The bigger-than-expected decline will likely have an impact on final first-quarter GDP figures, which are expected to be revised upward after an initial estimate of a 2.5 percent rise.
The drop in crude oil imports - which averaged 7 million barrels per day, the lowest level since 1996 - was a key factor in the narrower trade gap.
That figure reflects growing domestic oil and natural gas output.
The smaller trade deficit is a positive sign for the US economy, which has recovered slowly from the 2008-09 global recession.