Cyrus Hall McCormick was born in Rockbridge County, Virginia, the eldest son of Robert and Mary Ann McCormick. Though he received only a limited formal education, he showed a talent for mechanics and soon learned the skills of his father, who had been experimenting with farm machinery since about 1816. The elder McCormick patented a thresher and other farm machines, but none of them were commercially successful, and his attempts to build a mechanical reaper, a device capable of cutting grain, ended in failure. In 1831, Robert abandoned work on the reaper and Cyrus took over the project.

With a new perspective on the project, Cyrus built a machine that departed radically from his father's designs. (It is suspected that McCormick's black mechanic, Joe Anderson, may have played a major role in the reaper's development without receiving recognition for it). Its workings, including the gearings, reciprocating knife, projecting teeth, and...