Day was born in Washington, D.C..[1] He played college football at North Carolina A&T State University, where he was an all-conference player as a two-way lineman; he was also on the track team.
[1] In 1960, he was one of the original draft picks of the new American Football League (AFL) Buffalo Bills franchise.
[1] He was part of a Bills' defense that did not allow a rushing touchdown for 17 consecutive games over a portion of the 1964 and 1965 seasons, winning the American Football League Championship in both years.
[1] For his work helping indigent NFL former players, Day received the NFLPA Award of Excellence in 1997.
[1] He worked in radio sales and as a youth counselor and a teacher in the Buffalo school system, before becoming a supervisor at Harrison Radiator in 1977.