Jethro Wood was born on March 16, 1774. His birthplace may have been Dartmouth, Bristol County, Massachusetts, United States, the early home of his family, though the vital records of that town contain no mention of his birth. Some sources also mention White Creek, New York, United States, as his birthplace. Jethro was a son of John Wood and Dinah (Hussey) Wood.
Approximately in 1800, Wood, together with his family, moved to Cayuga County, New York, establishing his residence on a farm near Poplar Ridge, where he lived until his death.
Wood's fame rests upon his invention of the cast-iron moldboard plow with replaceable parts. He had difficulty in manufacturing and in inducing his neighbors to use the plow, which they thought would poison their land. Jethro continued to improve his original invention and, on September 1, 1819, received a patent for the plow, for which he was so well known. It was made by others without Wood's leave and he and his heirs waged a continual fight against infringers. His patent was extended for an additional period of fourteen years and near the close of this term, the infringement fight was finally won, but to little avail. A congressional committee, that investigated the question of a further extension of the patent, found, that Wood and his family had received $8,595 from his plow, but had expended most of it in costs and charges. A bill for a further extension of the patent was passed by the Senate, but was defeated in the House of Representatives. Later, the state of New York appropriated $2,000 for Wood's heirs.
Jethro has frequently been referred to as the inventor of the cast-iron plow, but cast-iron had been used in the Norfolk plow in 1721, and by 1791, plows with interchangeable moldboards, landsides and shares of cast-iron were known and in use in Great Britain. In the United States, cast-iron shares were made as early as 1794 and Newbold's patent for a cast-iron plow, made in one piece, was issued in 1797. Peacock's plow of 1807 was made in three pieces with the moldboard and landside of cast iron. That of Stephen McCormick, 1819, with its cast-iron moldboard, antedated Wood's second invention.
Wood's improvement over the existing models lays largely in the shape of the parts, particularly the moldboard. He vaguely described this as a kind of "plano-curvilinear figure" of peculiar shape, in which diverging lines from front to rear and at least one transverse line were straight.
The importance of longitudinal and transverse straight lines had been emphasized by Small, Pickering and Thomas Jefferson. The peculiar virtue of Wood's plow lays in the shape, resulting from the extended use of longitudinal straight lines and the combination of good balance, strength, light draft, interchangeability of parts, the use of cast-iron and the cheapness of manufacture. His design and principles of construction were copied throughout the North, as were those of Stephen McCormick in the South. For what he did to perfect the cast-iron plow and to bring it into extended use, he deserves much credit.
Wood died in poverty in 1834. He had spent his entire "large fortune" on perfecting his invention and litigating the patent, and had earned less than $550 in total from his invention. His invention was later supplanted by the further improvements of John Deere, who furnished the plow with polished plowshares, that enabled it to break up prairie sod.
Jethro was a Quaker throughout his life, but was not particularly doctrinaire.
Jethro married Sylvia (Howland) Wood on January 1, 1793. They had six children - Benjamin Howland Wood, Phebe Wood, John Wood, Maria (Wood) Foote, Sarah (Wood) Underhill and Sylvia Ann (Wood) Gould.
