Here's a sampling from some of the post-game reaction:
Chris Bascombe, the Telegraph:
Canada coach John Herdman, born in County Durham, suffered a cruel semi-final defeat to the United States in a breathless encounter which proved for pure entertainment the women are more than capable of eclipsing the men.
Spare a thought for Canadian skipper Christine Sinclair. She struck a hat-trick worthy of a commemorative plaque on the walls of Old Trafford, only to be denied in extra-time by Alex Morgan's 123rd-minute header. The US had earlier equalised three times.
This stadium has played host to many robust derbies, but the meeting of North American rivals brings a flavour of its own; a peculiarly satisfying simmering resentment that produced an exhilarating football match.
Andy Hunter, the Guardian:
It was a semi-final where both sides threw caution to the wind and the crowd of 26,630 at Old Trafford was captivated. When it was over, the reigning champions were simply relieved to be through and happy that their hopes of avenging last summer's World Cup final defeat by Japan were still alive. Canada, inspired by the outstanding Sinclair, were on the floor in tears and disbelief. Their coach, the Newcastle-born John Herdman, was aghast at the performance of the Norwegian referee, Christiana Pedersen.
Lucy Ward, former England under-21 team member and BBC Sport soccer commentator:
You feel for Canada but what a great winning header. What a cruel finish. I thought penalties would be cruel but that's even crueller. You just can't beat this USA team. It was the killer blow right at the end. It's soul-destroying for Canada but absolutely brilliant for the United States.
Paul Fletcher, BBC Sport:
You want footballing drama? There are 120 minutes on the clock when Alex Morgan scores the header that takes the US into the final, where they will face Japan on Thursday. An epic. Canada 3-4 USA. Harsh, very harsh, on Canada. What. A. Game. Of. Football.
John Molinaro, Sportsnet:
It would be wonderfully easy and convenient if we could just say Canada was jobbed by the referee and leave it at that.
But no matter how pleasant it may be to hear, the truth, as ugly as it may be, still has to be told.To pin Canada’s loss entirely on Pedersen’s shoulders is misguided and unfair. Canada’s inability to hold onto a lead, as well as some stretches in play where it ceded possession far too cheaply, had an equal bearing on the final result.
Pedersen played her part, but ultimately, it’s the Canadian players who bear the ultimate responsibility.
Jackie MacMullan, ESPN.com:
Brace yourself for the onslaught of conspiracy theories to abound. Much of the world believes the Canadians were robbed, and the heavily favored Americans will have few allies in the stands for their gold-medal bid on Aug. 9. That, of course, will be nothing new for coach Pia Sundhage and her team.