With many of the top U.S. players that compete for clubs in Europe given time off, Gregg Berhalter's MLS-heavy side jumped out to an early lead when Sam Vines headed home after a flicked-on Gyasi Zardes ball found him wide open at the far post.
It was Vines' first goal for the U.S. at senior international level.
Haiti responded well after conceding and showed poise for the remainder of the half as the U.S. took its 1-0 lead into the break.
The U.S. was unable to pad its lead in the second half, with substitute Nicholas Gioacchini looking dangerous and hitting the post from a wide-open shot as the match approached 70 minutes.
Vines, who plays for the Colorado Rapids of MLS, made a run to the back post and was in position for the pass off the foot of the Columbus Crew's Zardes for a header in his fourth match.
The assist by Zardes was his 10th in a U.S. uniform. Combined with his 12 goals, he came the second-fastest American male (57 games) to reach double figures in those categories. Landon Donovan accomplished the double-double in his 50th game on June 13, 2004.
The top two teams from the four groups advance to the quarterfinals on July 24 and 25.
Haiti, which was absent several players because of COVID-19 issues, had two good chances in the first half on Turner (New England Revolution) from Crew forward Derrick Etienne Jr. but each attempt was off target.
At the other end, Brian Sylvestre twice stopped headers by Walker Zimmerman (Nashville SC) in the first half.
A highlight for the fans at Children's Mercy Park was Gianluca Busio, 19, of Sporting KC making his U.S. debut. He forced a save by Sylvestre on a long volley in the 76th minute.
It was one of the few quality attempts for the U.S. in the second half against Sylvestre (four saves).
Defender James Sands and midfielder Eryk Williamson also made their debuts in the second half.
U.S. forward Paul Arriola left in the 14th minute with tightness in his right hamstring.
A moment of silence was held before the match to acknowledge the death of Haitian president Jovenel Moise, who was assassinated on Wednesd
Next up for the Americans is a second group-stage match against Martinique on July 16.