Born in Indiana, Ritter was educated at St. Meinrad's seminary, and ordained in 1917. He served as a pastor and rector in Indianapolis until 1934, when he was consecrated as Bishop of Indianapolis. As bishop, he directed the racial integration of the parish school system and reorganized the Catholic Charities in the diocese. In 1944, Ritter became Metropolitan Archbishop when Indianapolis was elevated to an archdiocese, and in 1946, he was named Archbishop of Saint Louis. In St. Louis, Ritter continued the work begun in Indianapolis, announcing the end of segregation in the parochial schools by the start the 1947-48 school year. Later he founded a diocesan mission in Bolivia, one of the first missionary endeavors not established by a religious order. Ritter was created a cardinal in 1961 by Pope John XXIII. He was an active participant at Vatican II, although he died of a heart attack before being able to implement many of its reforms in his archdiocese.