One of the questions about the green card is how long a permanent resident can stay outside the United States.
According to the U.S. government, a lawful permanent resident may leave the United States multiple times and enter as many times as necessary.
As long as you are not out of the country for one year or more. In this case, a re-entry permit must be applied for with the U.S. Citizenship and Immigration Services.
This allows a permanent resident to apply for admission to the United States upon return from abroad during the term of that permit.
Steps to return to the United States
Processing eliminates the need for a resident visa if returning from a U.S. embassy or consulate.
Reentry permits are valid for 2 years from the date of issuance. If a person remains outside the United States for a longer period of time, he or she is no longer allowed to enter the country.
To apply for a re-entry permit, an application for a travel document must be submitted.
If you have applied for permanent resident status but are unofficial and need to leave the United States on an emergency basis, you may apply for an early departure permit.
This is for departure from the United States and can be processed by filing an I-131 application.