Weston McKennie's uncontested header in the first half Sunday was the difference between the two sides.
Curacao, which upset Honduras to advance from the group stage, outshot and outhustled the U.S. at Lincoln Financial Field. But the underdog couldn't find a breakthrough.
The USMNT will face Jamaica in the final four Wednesday.
Gregg Berhalter's side registered just 47 percent possession against Curacao, its lowest total in a Gold Cup match since 2013, according to TruMedia's Paul Carr.
Christian Pulisic delivered one of the game's only moments of quality, lofting a spectacular cross into the box for McKennie to finish in the 25th minute.
Curacao played much better than its 79th-place ranking would indicate. Leandro Bacuna, one of the country's best players and a member of recently relegated Premier League side Cardiff City, almost made the host pay for its sloppiness in the 85th minute, but goalkeeper Zack Steffen extended his arm to tip the midfielder's fierce shot over the bar.