mskidw

As far as I know, you don't need all of those documents.. you can of course bring them if it makes you feel more secure but expired conditional green card, 18-month extension letter, and current passport is enough...
All these conditions, new and old can make anyone nervous...

I just came back to new York yesterday from China. I only brought expired green card and the extension letter. The custom officer only need these two. Only thing need to know is that let the people who control the line to use the anto print machine know your situation, they will directly send you to a line. The reason is the expired green card wont work on the auto print machine. So you just need skip this step. The people who work there gonna directly send you the line to wait to see the custom officer right away.
 
The whole process is very easy. I was worried so much before. The officer knew what to do. Expired green card, extension letter and your passport is what you need.

My conditional green card expired in September 2018 and I received my 18-month extension letter after I filed I-751 application. I am planning on traveling aboard for two weeks in September 2019.
 
I plan on bringing my expired conditional green card, 18-month extension letter, unexpired passport, and marriage certificate. 
 
1. Will these documents be sufficient enough to come back to US without issues?  
2. A lot of information on the Internet saying to get a stamp on the passport even though having an extension letter. But my local USCIS, Detroit, is one of the testing local office that eliminated online Infopass appointment and one can only schedule Infopass appointment by calling customer service. I called customer service several times before and they all told me that I could only schedule an appointment for the stamp one month prior to the expiration of the extension letter. So I do NOT think the stamp on my passport is a must to come back to US in my case. Am I understanding this correctly?
 
Thank you!

I was just want to share my story since I was worried myself before travelling with an extension letter.
 
We flew with Virgin Atlantic from London and the airline staff were fully aware of the extension letter and once we landed in Seattle my husband (USC) and daughter (USC) used the kiosk line got their receipt and then we've joined the X line so I could get through. The Custom officer was fully aware of the extension letter as well he didn't even look at it he just took my green card and stamped my passport in.
 
I was worried for no reason lol...