Locomotive "Pioneer" of the Cumberland Railroad

http://www.gutenberg.org/files/28160/28160-h/28160-h.htm

Pioneer was built by the Union Works near Boston, bought used by the Cumberland railroad in 1851, and retired after 30 years service. It passed on to the Pennsylvania RR when the railway was absorbed and for some reason was not scrapped. By 1901 it was considered a historical item and as noted above passed on to the Smithsonian in 1960.
Update June 2018.
 Now on display at the B&O museum in Baltimore, a very fine museum, if you're in the neighbourhood.