The four-time gold medallists defeated Mexico 4-0 for the second successive game, thanks to goals from former City star Carli Lloyd, Lindsey Horan and Tobin Heath, plus a Reyna Reyes own-goal.
The triumph marked the USA's final game before the Summer Games, extending their astounding unbeaten run to 44 games.
Dahlkemper completed another 90 minutes for the Stars and Stripes, continuing her impressive streak of minutes for her country, having tallied the most in both 2019 and 2020.
The USWNT will face Sweden on 21 July in Tokyo (4:30. ET, 17:30 UK time), New Zealand on 24 July in Satiama (7:30 ET, 20:30 UK time) and Australia in Kashima (4:00 ET, 17:00 UK time) on 27 July.