I have moved to Canada and have gotten my Canadian PR.
I have an on-going H1b status in the US, and have received I-140 for my US green card.
Is it necessary to officially update USCIS on my address change?
Also, on the USCIS website, I only see US-to-US address change (with US states as only option from drop-down). Is it possible to give Canadian address?
This is a tough one. From How to Report a Change of Address to USCIS - U.S. Immigration
“Therefore, if they temporarily move outside the United States, they must still provide a domestic (U.S.) address for all correspondence from USCIS within 10 days of moving. USCIS never sends correspondence to a non-U.S. address.”
“[…] no longer has their own address in the United States where they may receive postal mail, they generally may provide the address of a trusted relative or friend instead.”
That said, also keep in mind that you if have moved out of the country,
“You should still let USCIS know within 10 days of moving. If your immigration case is now being handled by the National Visa Center, it’s worth contacting them directly too in order to make sure they know your new address.”
So it seems like you should send an email or mail a letter via post to USCIS to let them know that you’ve moved to Canada, but maybe you don’t have to do the official address change online unless the address to get your US mail has changed with the move (e.g. because your old lease in the US has ended).
That said, have you really moved? Some folks do a “soft landing” where they land in Canada and give a Canadian address to receive the PR card but then move back as soon as they get their PR card.