A bright opening and goal in the ninth minute from Weston McKennie was interrupted by an 87-minute weather delay, but Christian Pulisic scored on either side of Shamar Nicholson's header in the second half as the host maintained control in Nashville's Nissan Stadium.
The USMNT will lock horns with Gerardo "Tata" Martino's Mexico in Sunday's final.
The U.S. was in charge from the very beginning and would've been ahead even earlier if it wasn't for some excellent goalkeeping by Andre Blake and heroic blocks courtesy of his otherwise disorganized defense. It was a pleasingly simple goal when the pressure did tell: Michael Bradley sprung a ball to the right from his No. 6 position, right-back Reggie Cannon side-footed it first time into the area, and McKennie arrived late to collect and finish.
Gregg Berhalter's ranks didn't reduce their pace - Blake did well to get a hand to Pulisic's free-kick before it hit the woodwork - but Jamaica was given an opportunity to regroup during the holdup due to lightning.
When the teams returned to the pitch despite there still being ominous flashes around the stadium, it seemed the Pulisic-inspired U.S. hadn't skipped a beat as it drove at Jamaica's goal. However, Zack Steffen was called into action in the 23rd minute when he stopped Junior Flemmings' powerful shot from distance.
Pulisic got his goal seven minutes after the restart. Jordan Morris was released by McKennie's beautifully weighted pass through the middle, and the Seattle Sounders forward's shot across goal was parried to the feet of Pulisic by Blake. Pulisic couldn't miss.
Gyasi Zardes, on the other hand, could miss. He seemed to dash any chance he had of starting over Jozy Altidore in the final when he somehow blasted a one-on-one comfortably wide of the goal within minutes of replacing the Toronto FC marksman.
Zardes was then at fault for Jamaica's lifeline. A loose touch from the luckless Columbus Crew attacker was jumped upon by Je-Vaughn Watson and followed by a Leon Bailey surge and cross. Substitute Nicholson rose to plant a tidy header past Steffen.
Bailey was dangerous but Pulisic ended the match when he nabbed his second three minutes before the end of normal time. He was instrumental in the move when he cut inside from the right-hand side and was eventually the beneficiary of another rebound when Paul Arriola's 20-yard shot was spilled by Blake.
The USMNT and Mexico have now squabbled in six of the 15 Gold Cup finals, and the former has emerged victorious in four of the previous five contests.