1904 United States 1-cent Louisiana Purchase Exposition commemorative stamp featuring Robert R. Livingston.

This is a 1904 United States 1-cent Louisiana Purchase Exposition commemorative stamp featuring Robert R. Livingston. 

• The green stamp (Scott #323) was part of a set of five issued to commemorate the centennial of the Louisiana Purchase and the 1904 St. Louis World's Fair. 
• Livingston was the U.S. minister to France and a key negotiator in acquiring the Louisiana Territory for the United States. 
• The stamp features two scenes depicting the diverse landscapes of the acquired territory: a swampy area on the left and a covered wagon representing the western plains on the right. 

• • These stamps were only sold during the fair and are considered scarce today.