This is the best resource I could find. I'm not certain if it should be trusted because I don't know the organization who maintains it, but the data is interesting.
http://atlas.xyvy.info/map/haplogroup-d ... nteractive
This shows Y-DNA Haplogroup Diversity by country.
As you can see, Canada is 0.45, while the US is 0.49. However, on a global scale, it looks like America is relatively middle of the road. Less diverse than Mexico and a big part of Central America, less diverse than a big chunk of the Middle East, Asia (minus China) and Russia, but slightly more to slightly less diverse than Europe. And of course Sudan, Chad and Egypt are off the charts.