Donald L. Day was born August 14, 1931, in Trail, Oklahoma. After graduating high school, Donald joined the U.S. Air Force ROTC. He was called to active duty and became a B-36 pilot with the Strategic Air Command.

Donald earned his B.S. degree from Oklahoma A and M in 1954 and his M.S. from the University of Missouri in 1959. In 1962, Don earned his Ph.D. from Oklahoma State University where he then went on to become a professor in the Agricultural and Biological Engineering Department at the University of Illinois for more than 32 years.

Through his work, Don traveled extensively, visiting 32 foreign countries on advising assignments.