The postmark from the Shanksville post office will include the image of the Flight 93 Memorial Chapel and was designed by its director, Bishop Alphonse Mascherino.
The Shanksville post office gets a few thousand requests for the special cancellation each year.
Customers can have their letters canceled from 8 a.m. to 4 p.m. at the post office on Tuesday, the 11th anniversary of the terrorist attacks which included the hijacked flight on which 40 passengers and crew were killed. Others can request the special cancellation by mailing requests to the post office within 30 days.
