I don't know the details, but be sure to check into what you need to do about rrsps and other investments you may have, as well as tax implications and then all the same questions again but in reverse for when you return.
Can't emphasize that ^^^ advice enough.
Moving part way through the year can bring unexpected taxes if you're not careful:
If you reside in the US for [HTML_REMOVED]183 days they will deem you to be a resident for the whole year. The state you move to will probably do the same. This means you pay US federal and state income tax on both your US and Canadian earnings for the entire year. Canada will also deem you to be a resident for the time you worked in Canada, as will your province - and you will have to pay Canadian/provincial taxes on this income.
Its not a big deal for federal taxes because tax treaties ensure you don't get bent over too badly. But there are no treaties between states and provinces. So, you will pay both state and provincial income tax on whatever you earned in Canada, and neither will give you credit for what you paid to the other. Ask me how I know all this…!
Canada is a little more into pro-rating so I don't think it's as bad if you reside in Canada for over half the year. But I think if you are a US resident for less than half the year you may lose your tax deductions, which can be a big deal.
And also important to note, even if you move to the US but maintain ties to Canada, the CRA can come back years later and deem you to be a Canadian resident for the whole time, and assess taxes, penalties and interest on what you earned in the US while away. So its important to cut ties to Canada (get rid of bank accounts, memberships, cell phones, cars you won't take with you, etc - having wife/kids remain in Canada is a definite tie). There is info on CRA's website about this and you can send them info to get an advance ruling on your situation before you go - highly recommended.
Like ceebee said, get professional advice because there are some complex rules you're dealing with here. And, make sure your employer gets you a green card. That way if you decide to stay, you have no issues doing so. A lot of other visas are tied to a specific employer.