Cash gift being wire transferred to U.S. from Canada

My Mother wants to wire transfer a rather large loan ($50,000USD) to me (Canada to U.S.). Will I have to pay any kind of tax on this money?

There is no tax on money being gifted or "loaned" by a Cdn to a US taxpayer. If it was over $100K it would need to be reported by you on form 3520, but there would be no tax to pay for either of you. I trust she is not charging you interest?

It doesn't matter where the money is kept or how it is sent to you.

I would have some paperwork showing that it is a loan however, so that the payments you make back to her (if greater than $13K in a year) are not considered gifts by you to her. That would be taxable in US.