Lusitania
Donor
That includes the Caribbean provinces. Also by 1900 with 50 years of self government and such Canada would be asserting its own will and at times it would not be same as londons.Well, the US would be completely overpowered by British Empire ITTL
As for over powering the US While it would Result in certain level of animosity between Canada/British empire and USA. The US would be strong enough to stand up to British/Canada. The huge difference is the Canadian constant fear of American invasion and or economic dominance during late 19th and early 20th century would be gone.
Also a Canadian saying that when sharing a bed with elephant we feel every twitch and turn would no longer exist.