Many folks don't know the extent of the historical feelings between older Notre Dame alumni and the B1G....I was quite amazed, when talking to Notre Dame grads, who were acquaintances, at how history still reverberated some 90 years later. It has been kept alive going from generation to generation.
Notre Dame, in the way back, did attempt to join the Big Ten and was rebuffed. In 1926 Knute Rockne, in his capacity as Irish athletic director, made a strong bid for Big Ten admission.
His effort was rebuffed by a group led by Michigan's Fielding Yost.
Hints of anti Catholicism are still bandied about...
Wiki...
Murray Sperber's book Shake Down the Thunder places principal responsibility for the Big Ten blackballing and boycotting of Notre Dame on Yost, as well as the charge that this was motivated by anti-Catholic and anti-immigrant prejudice common in the early 20th century.
1910 - 24 hours before Notre Dame and Michigan are to play, Yost cancels the game. The two teams do not play again for thirty-two years.
1911 - A general policy of blackballing of Notre Dame by Michigan and Western Conference schools begins. Jesse Harper (Notre Dame) writes to ask Michigan to schedule a game: "I am very sorry you could not think it best to schedule a game for next fall. If at any time you should find that your schedule is not working out to suit you and that you would like to play Notre Dame, I would be very glad to hear from you."
1926 - In a note to the Big Ten Commissioner, noting that Notre Dame had won its last twelve games against Big Ten teams Yost urges all to join Michigan's renewed boycott, "one can readily see how the Conference is helping Notre Dame."