Philatelic female firsts
While she may become the first female President of the United States, she won't be the first woman on a U.S. postage stamp.
Surprisingly, that honor goes to Queen Isabella of Spain who was featured on a $4 stamp issued in 1893 which commemorated the 400th anniversary of Columbus's discovery of the new world. The stamp (shown above) pictured her and Christopher Columbus as part of set that has become known as the Columbians.
The first American woman to be commemorated on a stamp of her very own was the first First Lady -- Martha Washington in 1902.