Where do I file my I-751?
Currently, all I-751 Petitions are filed at the Phoenix Lockbox.
U.S. Postal Service (USPS)
PO Box 21200
Phoenix, AZ 85036
FedEx, UPS, and DHL
1820 E. Skyharbor Circle S
Phoenix, AZ 85034
Before you mail out anything to USCIS always double check that the filing address has not changed. Go to: https://www.uscis.gov/i-751
Make sure to make a copy of everything you included and keep the tracking information in your records.
You should never send anything to USCIS through “regular mail”. You need to make sure that you have proof of filing should USCIS lose your petition.
USPS is extremely unreliable and even when you pay for priority mail it never gets there on time. The only pro is that the price might be less than other carriers. But at the end of the day, you need a carrier that is known for its reliability.
FedEx/UPS are your best options. They offer overnight service which is great if you wait until the last minute to file. Furthermore, you will have a tracking number to keep track of the mail.
Considering the importance of this filing, the last thing you want to worry about is if your package is lost in the mail. Spend the extra money and ensure that it is delivered in a timely and professional manner.