The cards and app work fine in the US. One oddity that did hit me a while back when using the app. Somehow my Canadian based account magically got converted to a US dollar account, possibly after hitting the reload threshold during a random US purchase. I had used the app on several US trips prior without issue; not 100% certain why this randomly happened. I had to call Starbucks to get my account converted back over to a Canadian dollar account as it started taking all my reloads in US$ from my C$ credit card, and I ended up paying exchange on both the purchase and reload transactions in Canada. I've used the app several times since in the US with no further issues.