Surrendering Green Cards

[crushing]

I'm an American citizen who has spent most of my life in Canada (became Canadian citizen when I was a child).  I recently moved my family down to the U.S. for three years for a job, and returned to Canada afterwards (that was about 5 years ago).  For the immigration, my wife and two sons were issued Green cards.  When we moved back to Canada, we were not asked to file any forms or surrender our green cards.

We crossed the border on the weekend in order for my wife to activate a student visa (she's attending college in Buffalo).  During this process, we were told we needed to surrender our green cards immediately.  As we did not have them with us, we were told to return to the border asap to surrender them before my wife began crossing for school.

We plan to do this in a couple of days, but I'm curious about two things:

1.  Once we surrender them will we have trouble crossing into the U.S. in the future with Canadian passports (we have done so many times, and this was the first time the green card issue even came up with customs officials)?

2.  I'm assuming what we were told is correct (upon doing some browsing I've learned that, if you take up permanent residence elsewhere, which we have in Canada, you are forfeiting your green card), but would like to hear any comments anyone has.

Thanks so much

[thaiguy]

This is really a Canadian immigration forum.  Your question is with U.S. immigration.

[Reba]

In order to remain a US permanent resident, you need to remain a resident of the US.  If you leave the US and take up legal residency in some other country (which you have) then you abandon your status in the US, unless you apply for a re-entry permit *before you leave* and if you are intending to be gone less than one year.  As you neither applied for the re-entry permit, and you have been gone more than one year, your permanent resident status in the US is abandoned.

From the USCIS website:

Maintaining Permanent Residence
Maintaining Permanent Residence You may lose your permanent residence status if you commit an act that makes you removable from the United States under the law in section 237 of the Immigration and Nationality Act. If you commit such an act, you may be brought before the immigration courts to determine your right to remain a Permanent Resident.

You may be found to have abandoned your permanent resident status if you:

Move to another country intending to live there permanently.
Remain outside of the US for more than one year without obtaining a reentry permit or returning resident visa. However in determining whether your status has been abandoned any length of absence from the US may be considered, even if it is less than one year.
Remain outside of the US for more than two years after issuance of a reentry permit without obtaining a returning resident visa. However in determining whether your status has been abandoned any length of absence from the US may be considered, even if it is less than one year.
Fail to file income tax returns while living outside of the US for any period.
Declare yourself a “nonimmigrant” on your tax returns.

(hopefully the tags work)