"Be prepared for a delay in receiving your green card or EAD card in the mail. USCIS has confirmed that the card production facility in Corbin, Kentucky, is undergoing maintenance, and that all card production work was transferred to the facility in Lee’s Summit, Missouri. As a result, there is a backlog of cases in Lee’s Summit, and clients may not receive their cards until two to three weeks after approval of the underlying application. USCIS anticipates that the backlog will be resolved sometime next month".

http://immigrationgirl.com/alert-expect-delay-of-2-to-3-weeks-to-receive-green-card-or-ead-after-approval/