Scotland left Houston embarrassed as they became the first Tier One nation to lose to the United States.
They conceded two tries to Worcester hooker Joe Taufete'e and a gift score to flanker Hanco Germishuys to throw away a dominant first half with an error-ridden second.
Former Blackrock college student and Connacht fly-half AJ MacGinty, now with Sale Sharks, was pivotal at 10 for the history-makers.
Scotland did give themselves a chance to win the game three minutes after the 80 minutes were up when Adam Hastings found the killer pass to put Dougie Fife, the replacement wing, in for their fourth try, but the touchline conversion proved to be too tricky for Blair Kinghorn.
All that after the perfect start as new captain Stuart Hogg was given a tiny sliver of space on the outside of the American defence.
He needed no second invitation, slicing through and proving a perfect pass to Kinghorn on the wing for the opening try.
With the young wing converting, it was just the settler they were looking for.
Any idea that it was going to be an easy ride for the Scots was, however, quickly dismissed as the USA started to get their big forwards into the game, pummelling the Scots defence and forcing a string of penalties.
In the end, when they got an easy shot from in front of the posts and MacGinty took the points.
Scotland could have restored their seven-point advantage from the kick off but Kinghorn was narrowly wide with a shot from the 10 metre line.
It only delayed the Scotland score, however, as they set up camp in the home 22 until Peter Horne wriggled out of a tackle and found his brother George there to make it almost to the line.
At first it looked as though he had managed to touch the ball against a post for try but after lengthy review, the officials did not have a camera angle that showed one way or the other.
Instead referee Wayne Barnes ruled the tackle to stop him had been high and awarded a penalty try with Manu Samoa, the USA lock, being sent to the sin bin.
A superb solo break from MacGinty, who plays for Sale Sharks in the English Premiership, reminded the Scots that they still had work to do, though they did hit back with another try from a line out maul, George Turner, the hooker, providing the touch down, just as he had done three times the week before.
The Americans were not finished and when Scotland spilled the ball at the kick off they simply hammered at the line until eventually Taufete'e, the hooker, grabbed their first try, though Kinghorn opened a bit more daylight between the sides with a penalty on the stroke of half time.
They needed it, as the USA won a line out yards from the Scotland line, and again the visitors had no answer to the power of Taufete'e on the charge from the back of the maul, reaching out to ground the ball with two Scots clinging on.
MacGinty converted and added a penalty and suddenly it was a one-point game.
Scotland rang the changes to freshen up the side and find a way into the match but it only got worse for them as an exchange of kicks ended with Matt Fagerson dropping the ball and MacGinty swooping on it to put flanker Germishuys over for the go-ahead try.
Scotland came close to getting back in front with a solo break from Kinghorn to set up the position and Bennett, the replacement centre, going over but losing the ball as he tried to ground it.
It all set up the dramatic finale for Fife and Kinghorn and sent the American fans home happy as the Scots were left to regroup ahead of their game in Argentina next week.
"We gave them momentum in that third quarter through ill discipline," said Gregor Townsend, the head coach as he reflected on the period that had turned the match the American way.
"A couple of penalties gave them field position. They had a lot of possession in that area and got a try through an error - which happens especially when the ball is slippery.
"It certainly was not the plan. We felt we had done some good things in the first half and when we added pace to the game we found space and scored those tries.
"I still felt we could have been better but it was a shame that did not happen, obviously. The third quarter was when the game changed.
"We did not finish early enough, Mark (Bennett) had a chance with 10 minutes to go and we had a couple of line out drives and got close to the line and got penalties but we left it too late."
Predictably, Gary Gold, the USA coach, was delighted, more with the way the team played than the result, pleasing though it was.
"The character that was shown by this group of players was immense," he said. "I know you won't believe this is the truth but winning or losing was not our priority but I wanted to seen how far we could progress when we play against world class opposition.
"At 23-13 down at half time with three pretty soft tries and teams could have capitulated but we just hung in there with the fight. Even if they had kicked the conversion at the end I would not feel different than I do now, it is good to know we have such a wonderful group of players.
"It is unbelievably satisfying but there is a process we have to go through now; there is no magic wand. It was obviously very pleasing if we could play like that and get the victory, that is why we play the game. I am just very proud of the guys."