Lived: 1809-1884 Cyrus McCormick was the American inventor of the mechanical reaper, a landmark invention that gave farmers the ability to harvest the seas of grain that characterized the Midwest United States. In 1831, McCormick completed his first reaper, patenting the device and working to see its widespread adoption throughout the country. That year, he sold two. Yet further improvements on his machine, as well as a move to Chicago and the creation of one of America's first mechanized factories turned Cyrus McCormick's invention into a staple of farming throughout the country. And it made McCormick a millionaire.