The 1-cent green stamp commemorating Chicago's Century of Progress International Exposition (1933-1934) depicts Fort Dearborn, the pioneer outpost that had been located at the mouth of the Chicago River. The fort was built as an army outpost in 1803 and named for Secretary of War Henry Dearborn. In 1812 Indian uprisings encouraged by the British forced evacuation of the fort and led to a massacre of many of the evacuees. Rebuilt in 1816, the fort was used off and on until the 1850s. The stamp's vignette pictures the blockhouse and stockade fence and other buildings of the fort in the background.