Sorry if this is not an intelligent question, but I am new to all of this. What is the difference between a District office and a Processing Office/District? I noticed on the website that you can check current processing times at either. Answers anyone? Thank you!!!

I will try my best to answer your questions. Processing centers work on immigration petitions. For example, I-130 for a family based petition and I–140 for an employment-based petition. Once your family based petition is approved by a processing center, you can file AOS at your district office when an immigration visa is available to you immediately. For employment-based immigration, you must file at a processing center. However, processing center may transfer your case to your district office for a further interview if they need to conduct additional investigation. There are 4 processing centers and 33 district offices in the United States. The processing time at a processing center shows estimate time frame to approve I-130 (Family), I-140 (Employment), I-485 AOS (Employment) and others. District processing time shows I –485 AOS (Family) and others.

Thank you very much, familybased for your answer. I'm assuming that one would file I-485 AOS (Family) through a district office then? Again, thanks in advance!

See http://www.visajourney.com/faq/index.htm#step%204