Just noticed that many casinos are putting your CDN Social Insurance Numbers on the 1042S forms. This is causing some confusion for the IRS.
It would be a good idea to travel with your ITIN (if you already have one). If you do win an amount that is taxable in the US (normally over $1,200), give the casino staff your ITIN. This will make the US Tax Refund process flow much smoother.
Happy Easter everyone.