The host nation's home advantage could not prevent the tie-breaking goal from Leroy Sané in the 57th minute of Saturday's match before a sellout crowd of 63,636 at Chicago's Soldier Field and Germany will take a nine-game winning streak into the World Cup.
Kai Havertz put four-time champions Germany in front with a header from a free kick in the second minute but Antonee Robinson tied the score in the 37th with a left-foot volley from the top of the arc following Christian Pulisic's corner kick.
The 16th-ranked United States have lost nine straight games to European opponents dating to 2022.
Hosting the World Cup for the first time since 1994, the Americans open against Paraguay on Friday, then play Australia and Turkey. The US hadn't lost their last match heading into a World Cup since 2002.
The Americans generated a handful of promising scoring opportunities, led by star Christian Pulisic Pulisic and Folarin Balogun. The 16th-ranked Americans also finished with 10 corner kicks, compared to two for the 10th-ranked Germans.
But they also made a couple of costly mistakes that coach Mauricio Pochettino will look to clean up.
"I think was an even game," Pochettino said. "If you see the stats, similar stats in some stats for us. I am so happy with the commitment and how the team was."
The Socceroos' first-up World Cup opponents Turkey notched a 2-1 win over Venezuela in Florida in their last warm up match before tackling the Aussies in Vancouver next Saturday.
Down after Venezuela's Gleiker Mendoza opened the scoring in the 13th minute, Turkey responded with goals to Baris Alper Yimaz (44th) and Yunis Akgun (54th).
The busy day of friendlies saw some of the biggest stars on display, with Cristiano Ronaldo, Vini Jr and Mohamed Salah playing, but three-time champions Argentina opted to rest Lionel Messi against Honduras in Texas in a game where forward Lautaro Martinez shone with a goal and one assist for a 2-0 win. Simeone scored the second goal.
Five-times champion Brazil beat Egypt 2-1 in Cleveland with Bruno Guimaraes scoring early from inside the box and Endrick adding in the second half, while Salah played the first half.
There was some drama with Brazil right back Wesley leaving the field in tears after what appeared to be a serious leg muscle injury.
England captain Harry Kane's sublime header in first-half stoppage time secured his team's first win of the summer as Thomas Tuchel's side scored a comfortable 1-0 victory against New Zealand in Florida.
England were in control from the outset against the World Cup's lowest-ranked team and Tuchel entirely changed his team at half-time.
Ronaldo captained Portugal as they defeated Chile 2-1 in an ill-tempered clash in Oeiras where both teams finished with 10 men as Rafael Leao and Ivan Roman received their marching orders.
Striker Romelu Lukaku continued his comeback from injury for Belgium with 25 minutes off the bench as they enjoyed a 5-0 victory over 10-man Tunisia in Brussels.
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