At my company many of the new hires are within Canada. You get similar talent, similar culture, native English, and same time zones for about 2/3 the cost of a USA dev.
You also don’t have to pay for healthcare of your Canadian employees since they pay for it on their income taxes.
Being in the UK I see a lot of that too - we're cheaper than Americans, speak the same language, are pretty close culturally, and while we're a few timezones off, we're far enough east to overlap with both the West Coast and India.
Plus, London alone has 10 million people, and if you lump in the London commuter belt that adds up to aroun 15 million people, more than all of Ontario! That's a hell of a skilled worker base to work with.
You also don’t have to pay for healthcare of your Canadian employees since they pay for it on their income taxes.