Gross domestic product expanded at a 3.1 percent annual rate, the Commerce Department said in its third estimate on Thursday, up from the 2.7 percent pace reported last month.
It was the fastest growth since late 2011 and also reflected a slightly better pace of consumer spending than previously estimated.
Economists polled by Reuters had expected GDP growth would be raised to a 2.8 percent pace. Exports grew at a 1.9 percent rate, rather than 1.1 percent.
