Cdn. Citizen, Live in U.S., Work in Canada

My job will have me on temporary assignment in Niagara Falls, Ontario for six months. I am a Canadian citizen. I know there is a six-month limitation on visiting the U.S. Can I legally live in Niagara Falls, N.Y. for my six-month assignment and commute daily to Ontario? I have a NEXUS card as a matter of convenience.

No. Living and visiting are two very different things. It will be very easy to determine at the Border that you are living in the USA.

Why would you want to do this?

You're being a bit vague - are you entering as a regular B-1 business visitor or are you going in as L-1, TN-1 or something like that?

If you're going in as L-1 or TN-1 then you can establish your residency in the US.

Going in as B-1 to work for six months is legally difficult although it is possible in certain situations. You can certainly remain there while the work is done but you can't make it your principal residence.

He is a Canadian, working in Canada, and wanting to reside in the USA.

Nope.

I missed the Ontario bit at the end of Niagara Falls. No, you can't live in the US and commute to Ontario.