I know the USPS is supposed to be standardized, but the level of service just isn't the same across the whole country. Mail in general is hit or miss, but I've often found wild discrepancy with seemingly random US destinations.

Package to up-state New York ends up taking 3 weeks while another to California sent on the same day takes 4 days.

Some of it is going to be due to routing and I have absolutely no idea how mail is routed out of Canada. I can add it to the few other things I don't get. Like Twitter, Facebook and Flickr.