Green Card through marriage processing time difference among different states

You don't provide many details, but let's assume you're a US citizen and you're filing an I-130 and I-485. These cases all go to Chicago Lockbox. Some immigration petitions will route to different centers based on the state of residency. However, you don't have to worry about that in the instant matter.

If you are fling an I-130/I-485 package together based on marriage to a U.S. citizen, all family based packages go to a USCIS lockbox in Chicago and the case is then processed by the USCIS National Benefits Center. You and your U.S. citizen spouse will be required to appear for an interview before an immigration officer at the local USCIS field office in the state where you reside - the processing times may differ for various USCIS field offices in different states.

Those types of applications are all filed to a central drop box and then may be routed to the district office based on your state of residence - you cannot choose where the application or interview takes place. In order to make sure your application is prepared and filed properly, you should consult with an immigration attorney.

Family-based petitions are processed by centralized Lockbox in Chicago, and only then are forwarded to Field Offices for scheduling, the average processing time is 6-8 months. Your case will be forwarded to the Filed Office that is covering your physical address. This means you cannot chose where exactly you will be interviewed.

No one will be able to tell you this. You have to use your physical address on the petition as you will be called for the interview and fingerprints. If you want the process to go faster, make sure your documents are in order and there is plenty of evidence to prove real marriage.

The cases are processed centrally then routed to a local office for interview. The times frames vary somewhat but the location where the interview occurs is dependent upon your place of residence.