Open daily 10 a.m. to 5:30 p.m.
Admission is always free!
2 Massachusetts Ave., N.E.
Washington, DC 20002
The museum's main entrance is located on the corner of First Street and Massachusetts Avenue NE. Other entrances have variable hours.
After the invention of stamps, handstamps were used to cancel the postage and guard against their re-use. Though this initial function has never changed, handstamp markings have changed over time to provide more information.