In USA/Canada we end up with population pimples with little in between. This is perfect for HSR, since there are very few required stations between primary cities.
Ottawa-Montréal, for example, is ~200km apart with no major centers in between, so an HSR can cross that distance with no stops
Toronto-Montréal is ~550km apart, with one possible stop in Kingston if the train splits for Ottawa. Again an HSR could make great time here. With the TGV’s 270kph station-station time, it would be 2 hours, slightly faster than flying + security (2h10-2h30) and less than half the driving time.
I’m knot as knowledgable about US geography, but I’m positive there and many city pairs like this on the east and west coasts.