Seaman Asahel Knapp (December 16, 1833 – April 1, 1911) was a Union College graduate, Phi Beta Kappa member, physician, college instructor, and, later, administrator, who took up farming late in life, moving to Iowa to raise general crops and livestock. In the view of many, a farm demonstration at the Walter G. Porter farm, now a National Historic Landmark in Terrell, Texas, set up by the Department of Agriculture at the urging of concerned merchants and growers, was the first in a series of steps that eventually led to passage of the legislation that formalize Cooperative Extension work.