You would still be a resident of Canada as long as you keep your permanent ties to Canada and are only in the USA on a temporary basis.
Your TFSA/RRSP continues as normal as long as you're a Canadian resident. Just remember that you will need to file both a Canadian residency return and a US nonresident return.
If you are a "resident of Canada" and only in the US on a temporary basis, then
- Make sure you maintain what a Canadian resident needs (e.g. home address, cdn bank accounts, cdn driver's license)
- File normal Canadian taxes, as a Canadian resident, and report all your worldwide income to CRA
- With the US, file 1040NR (you're a US non-resident alien)
- Keep using your TFSA, RRSP and all bank accounts as normal
