Pan-American issue 1-cent invert postage stamp
<a href="https://en.wikipedia.org/wiki/United_States_Post_Office_Department" class="extiw" title="en:United States Post Office Department">United States Post Office Department</a>
1901-05-01
Robert A. Siegel Auction Galleries 2007 Rarities of the World auction held 2007-06-16 <br>Lot 937 <a rel="nofollow" class="external free" href="http://www.siegelauctions.com/2007/937/207.jpg">http://www.siegelauctions.com/2007/937/207.jpg</a> <br>upload by <a href="//commons.wikimedia.org/wiki/User:BFolkman" title="User:BFolkman">BFolkman</a>