Newbold’s plow gave way to Jethro Wood’s three piece cast iron plow that allowed for interchangeable parts. The full potential of a metal plow was not realized until John Deere began manufacturing steel plows in the 1830s. Steel was lighter and stronger than the very brittle cast iron previously used. In addition, the increased use of horses to pull plows allowed for even greater success and lead to further innovation.
The significance of the plow to American history is outlined by the fact that even in 1860, nearly 60% of Americans were farmers, and agriculture accounted for 75% of our annual exports. Innovations in agriculture directly affected the American economy then and now.
Sources:
1. http://www.todayinsci.com/Events/Plow/Plow_CastIron.htm
2. http://www.agclassroom.org/gan/timeline/1860.htm