This 13 cent airmail stamp in black and red (Scott C62) depicts an image of the Liberty Bell and the words "Let Freedom Ring". The same stamp design had been issued a year earlier in a
black and green design with a 10 cent denomination (Scott C57).
From the U.S. Stamp Gallery website:
The Liberty Bell first was hung in 1753 in the newly finished Pennsylvania
State House. That building later became known as Independence Hall.
An inscription on the bell reads, "Proclaim Liberty throughout the land" (Lev.
25:10). The bell was rung on the adoption of the Declaration of Independence in
July 1776, inaugurating an Independence Day tradition that was observed every
year (other than 1777-1778, when the bell was removed and hidden from British
occupiers of Philadelphia) until 1846.
In 1846 a small crack in the bell enlarged to the point where the bell no
longer could be sounded.
The Liberty Bell may be the most famous symbol of the Colonial struggle for
independence. It now is housed at Philadelphia's Liberty Bell pavilion.
The National Postal Museum website has no narrative, only the stamp's technical details