Cyrus McCormick reportedly designed, built, and tested his reaper all within six weeks at Walnut Grove, although the design may have been merely an improvement upon the similar device developed by his father and his brother Leander over 20 years.
According to reports, Cyrus McCormick created, built, and tested his reaper within six weeks at Walnut Grove. However, it's possible that his design was an improvement upon the earlier model developed by his father and brother, Leander, over two decades before.