Emily Sonnett and Mallory Pugh scored first-half goals before Ashley Sanchez added a third in injury time to seal a victory in a semi-final played in sweltering conditions at Monterrey’s Estadio Universitario.
Canada advanced with a 3-0 victory over Jamaica in the second semi-final, and the winner of Monday’s final will secure an automatic qualifying berth to the Paris Games women’s football tournament.
Against Costa Rica, the world champions took their time before finally asserting their superiority with two first-half goals.
Alex Morgan signaled the US women’s attacking intent early on, missing a golden chance to open the scoring after three minutes when she prodded wide.
Morgan missed another opening after 17 minutes as the US steadily cranked up the pressure.
The breakthrough came in the 34th minute from a corner from the right-hand side.
Lindsey Horan’s flick looped up onto the wordwork and Sonnett jabbed it home from close range on the rebound.
Morgan had the ball back in the net two minutes later after finishing from a Horan pass, but the goal was disallowed for offside.
Sophia Smith should have made it 2-0 on the stroke of halftime after being played into space by Morgan, but rushed her finish and shot directly at Costa Rica goalkeeper Noella Bermudez.
But the US made it 2-0 moments later when Smith won possession high up the field.
Rose Lavelle’s clever backheel released Pugh and the winger rifled in a low-angled shot across Bermudez.
Canada seized an early lead in their match as Jessie Fleming headed in a cross from Ashley Lawrence in the 18th minute.
Fleming nearly doubled the score in the 36th minute, but Jamaican keeper Rebecca Spencer gathered up her curling shot and it was 1-0 at halftime.
The Canadians finally built on their lead in the 64th, when Adriana Leon’s cross from the right found Allysha Chapman racing into the box, Chapman nodding in a header.
Leon capped the scoring in the 76th.
While Olympic qualification will be at stake in the final, the eight-team tournament also doubles as a qualifier for the 2023 Women’s World Cup, with the four semi-finalists — the United States, Costa Rica, Canada and Jamaica — all securing tickets to next year’s tournament in Australia and New Zealand.
Costa Rica and Jamaica still have a shot at the 2024 Olympics. The winner of the third-place playoff and the tournament runner-up will meet in a playoff next year to determine another Paris berth.