In 1850, E. W. Quincy of Illinois patented an open-roll ear-snapping mechanism. A series of innovations led to corn heads for combines. Harvesting corn with corn pickers using open rolls on corn pickers after 1925 proved to be dangerous as farmers often needed to clear stalks from the rolls. In 1885, E. M. Aiken, Dawson, ND, patented shielded snapping rolls with flat plates above the rolls. C. K Shedd and E. V. Collins, Ames, IA, patented a more aggressive shielded snapping device in 1941 which was later used on sweet corn pickers. After 1945, the drying of high moisture corn became economic and proved to be a key to the development of field shelling for corn.
In 1952, C. Morrison, Deere & CO., Moline, IL, successfully harvested corn with a self-propelled combine and a corn head with shielded snapping roll units. This followed work on shelling corn with a combine cylinder by G.E. Pickard and D.F.Hopkins, Urbana, IL. In 1955, John Deere commercially sold cornheads for combines with shielded snapping rolls produced at Ankeny, IA. By 1965, corn acreage harvested by combines exceeded that harvested by corn pickers. In 1966, 26,000 corn heads were sold. In 1997, corn harvest was dominated by combines using heads with shielded snapping rolls which have proven to be efficient and safe.