Hello Jonathan,
Sandra here from the iTunes Store. I understand you have moved from Canada to the Untied States and are having an issue locating a few of your applications. I can certainly appreciate your concern and eagerness to regain access to your applications therefore I will do my best to address this for you today.
Regrettably, when you move between countries and change the country associated with your iTunes account you are unable to redownload the application on the US store if you have purchased it in the Canadian Store.
If you are unable to locate the application you can search your hard disk by following the steps in this article:
iTunes: Finding lost media downloads http://support.apple.com/kb/TS1408
If you have items on your iPhone, iPad, or iPod, you may use iTunes to transfer them to your computer. This article will walk you through that:
iTunes Store: Transferring purchases from your iPhone, iPad, or iPod to a computer http://support.apple.com/kb/HT1848
I apologize for any inconvenience this may have caused Jonathan. If there is anything further I can assist you with please let m know. Take care and enjoy your day.
Sincerely,
Sandra iTunes Store Customer Support
Please Note: I work Sunday, Monday and Wednesday 10:00 am - 6:30 pm EST
Thank you for allowing me the opportunity to assist you.