For those contemplating shipping...

Google is your friend; we've known about 2 options before: Gaylord FedEx, and the National Harbor UPS Store.

Looks like there is also an Amazon Locker:

Amazon Locker - Doyle

111 N Cove Ter, at Sunoco, Oxon Hill, MD, 20745-1179

The Gaylord has a business center which includes a FedEx, it's the most convenient but also rumored to be the most pricey

Gaylord FedEx - https://local.fedex.com/en-us/md/oxon-hill/office-5629

201 Waterfront St, Oxon Hill, MD 20745

(301) 567-0457

The UPS Store: https://locations.theupsstore.com/md/national-harbor/145-fleet-st

145 Fleet St, Oxon Hill, MD 20745

(301) 749-2094