 Cyrus McCormick was an uncle of Robert Sanderson McCormick (son-in-law of Joseph Medill); granduncle of Joseph Medill McCormick and Robert Rutherford McCormick; and great-granduncle of William McCormick Blair Jr.

McCormick had always been a devout Presbyterian, as well as advocate of Christian unity.He also valued and demonstrated in his life the Calvinist traits of self-denial, sobriety, thriftiness, efficiency, and morality.He believed feeding the world, made easier by the reaper, was part of his religious mission in life.