<a href="https://en.wikipedia.org/wiki/Arbor_Day" class="extiw" title="en:Arbor Day">Arbor Day</a> 2-cent 1932 issue U.S. stamp. The stamp's issue date coincided with the 100th anniversary of the birth of the founder of Arbor Day, <a href="https://en.wikipedia.org/wiki/Julius_Sterling_Morton" class="extiw" title="en:Julius Sterling Morton">J. Sterling Morton</a>.
Bureau of Engraving and Printing
U.S. Postal Service; National Postal Museum: <a rel="nofollow" class="external text" href="http://arago.si.edu/category_2033011.html">Arbor Day Issue</a>