American surveyor James Thompson produced the first plat of Chicago for the Illinois and Michigan Canal Commissioners.

James Thompson was an American surveyor who created the first plat of Chicago. Born in South Carolina, Thompson moved to Kaskaskia in southern Illinois as a young man and lived in the area for the rest of his life, working primarily as a surveyor. He was hired to plat settlements at the ends of the proposed Illinois and Michigan Canal in northern Illinois; he completed the plat of Chicago, the settlement at the eastern end, on August 4, 1830. After completing his survey of Chicago he returned to the Kaskaskia area and declined an offer of land in Chicago in favor of a cash payment. In addition to his surveying work, he served in various positions such as probate judge, county commissioner, and officer in the Illinois militia during the Black Hawk War.