Hi,
I am now in the process of applying for the unconditional green card. I have a conditional GC (marriage based) that expired March 09. After I sent in my application for the unconditional GC, I received a letter from the USCIS that they extended the validity of the conditional GC by one year (while they're processing my application). I now want to visit my family for Christmas (we finally can afford it), and was wondering whether I need to have the letter stating my GC was extended with me? How will they know on my way back to the US that it was extended? Does anyone here have any input?
Thank you.

Carry that letter with you at all times and when traveling internationally.

Thank you,
I do need to make a copy of it and carry it with me...Thanks for the reminder

If you travel internationally, you must carry the original. Make a copy and keep the copy at home.

You can carry a copy. CBP can access the databases showing the original issue of this form.