Alana, it is possible - I've ordered from Gap.com and Athleta, which are under the same umbrella. They ship with borderfree (or whatever it is called these days), a service I dislike.
Pros: Greater selection on the US site, you know the "landed cost" including duties and taxes right up front
Cons: shipping is slow, shipping + taxes + duties are expensive, the returns come with ridiculous processing fees, you can't apply coupon codes
Ditto Glory, though - is the top a new arrival? I have also noticed that things tend to pop up on the US site first. A particular colour of trousers I was eyeing on the US Banana republic site took a couple of weeks to pop up on the Canadian site.