By Appointment Only Closed Federal Holidays. The unique digits for each of our agencies and centers are in the expandable box on this page under "Our Locations.". PO Box 1010 Sterling, VA 20166-1010. Things Home across all styles and budgets you are able to submit your United passport! PO Box 1108 Sterling, VA 20166-1108 Hours: 8:00 a.m. to 4:00 p.m. Monday through Friday. CA/PPT/WPC charleston passport center 44132 mercure circle sterling virginia po box 1031.