Once you're legally married in the USA, do you have to register your marriage in Canada, too?

ooooh good question... but I doubt it

i didn't.....but then again, I don't know if I am supposed to!

No.

No, although if you have pension plans or such still in Canada you may wish to notify them that you have a spouse who may be a beneficiary if something happens to you.:-)

We got married in Jamaica and did not register our marriage in either Canada or the US. I don't think it's necesary as your marriage cert. is proof you are legally married.