My green card expires in about 4 months and I applied for renewal but I have not received the new card yet. I need to travel outside the US for a family emergency. Can I still travel with the receipt notice

In many situations the receipt notice for the I-90 renewal extends the validity of the green card for a certain period of time. If your receipt notice specifically says your status is extended, airlines and border officers generally accept that along with the expired card. Before traveling, it is a good idea to confirm the extension period and carry a copy of the receipt notice and your expired card.

Travel may still be possible depending on what your receipt notice says. Some renewal notices extend permanent resident status for up to 24 months. If you are unsure, you can also request an appointment at a USCIS office to get an I-551 stamp in your passport which serves as temporary proof of permanent residency while the new card is pending.