QUOTE(tweety @ Nov 14 2007, 12:51 PM)

I've looked all over the USCIS website, and while I couldn't even access some parts anymore (error messages all over the place), I cannot find a physical address for the service centers anymore (

they used to be on the website there somewhere, but as said, I can't find it).
The physical addresses for overnight delivery are still there for each service center -- go to the page linked below and click on the link for the applicable service center -- the page for each center has both the P.O. boxes and the physical addresses.
USCIS Service CentersNow that I think about it, the BEST advice is probably to send it overnight via USPS Express Mail. If you send it overnight via USPS Express Mail to the P.O. box -- the only way one can overnight to a P.O. box -- you stand a good chance of it arriving after the person from the service center picks up the mail. We see posts all the time from people freaking out when that happens because of the notice posted on the USPS tracking page about the package possibly being returned as undeliverable. If you send it FedEx or UPS to the physical address, you don't get the benefit of the USPS postmark.
So, having heard argument and being fully advised in the premises, I HEREBY ORDER AND ADJUDGE that the preferred method for getting a petition to a service center as promptly as possible is via USPS Express Mail to the physical address of the service center.
DONE AND ORDERED this 14th day of November, 2007.