Born in Detroit, Thomas Forsyth entered the fur trade about 1790 and with his half-brother John Kinzie, established a trading post at Chicago. By 1812 when he was appointed subagent, Forsyth was also operating a trading post at Peoria. As Indian agent for the Sauk and Fox in Illinois and Missouri, 1818-1830, he headquartered at Rock Island, but after his removal in 1830 he retired to St. Louis, where he wrote about his experiences and his observations of Indian language and customs.
