Ben Cima held his nerve to kick an 80th-minute penalty from inside his own half to secure a 19-18 victory for the USA and with it the final place at the World Rugby U20 Trophy 2016.
Cima had missed an effort only minutes earlier at Dell Diamond Stadium in Austin, but made no mistake when given another opportunity in this one-off match to determine the Rugby Americas North regional qualifier for the U20 Trophy.
The Junior All-Americans will now join hosts Zimbabwe, Fiji, Hong Kong, Namibia, Spain, Uruguay and Samoa, the side relegated from the U20 Championship in 2015, in the 19 April to 1 May event in Harare.
"We couldn't have picked a better group to represent the US," said interim coach JD Stephenson after ending a four-game losing run against Canada in his first match in charge.
"We couldn't have picked a better group of guys for what it stands for and who have pride in that jersey. It's just awesome."
Canada thought they had kicked the winning penalty when, with four minutes to go, fly-half Robbie Povey sent his effort through the posts but they were to suffer heart-break a few minutes later.
The Canadians, who lost the U20 Trophy final to Georgia last year, had led 15-9 at the break after tries from winger Trenton Cooper and replacement Peter Milazzo but Lorenzo Thomas' 50th minute try had given USA the lead again.
Photo credit: Travis Prior