The U.S. trade deficit fell in March for a second consecutive month as imports posted their biggest decline since 2009 and the daily flow of imported oil dropped to the lowest level in 17 years, the government reported Thursday, providing new evidence of slowing domestic demand. The Commerce Department said the trade deficit narrowed 11 percent to $38.8 billion, the second-smallest deficit since January 2010. Economists expected a bigger deficit of $42 billion. Imports fell 2.8 percent to $223.1 billion in March, the biggest percentage drop since February 2009. The decline in imports of goods was broad-based, adding to evidence of weak domestic demand, but the drop was led by a 4.4 percent drop in foreign petroleum. Crude-oil imports averaged only 7 million barrels per day, the lowest level since March 1996. Exports fell 0.9 percent to $184.3 billion, as sales of machinery, autos, and agricultural products declined. Sales of civilian aircraft rose.