Glennon was born on June 14, 1862, in Kinnegad, Ireland, the first of eight children of Matthew Glennon and Catherine (Rafferty) Glennon. His father immigrated to the United States in 1851, working for a time for the Pennsylvania Railroad before returning to Ireland in 1859 and marrying the following year.
Young John spent his boyhood on the family's sixty-acre farm, attended the local primary school in Kinnegad, the diocesan college of St. Mary's in Mullingar, and completed his philosophical and theological studies for the priesthood at All Hallows College in Dublin.
At the invitation of Bishop John Hogan of Kansas City, Glennon came to the United States in the fall of 1883 and was ordained for the diocese of Kansas City by special dispensation at the early age of twenty-two on December 20, 1884. Father Glennon served first as an assistant in St. Patrick's Church in Kansas City for three years and then returned to Europe for several months to visit his family in Ireland, to enroll in classes at the University of Bonn, and to study the German language so common among the Roman Catholics of Missouri. On his return, he was appointed secretary to the bishop and rector of the cathedral, and, in 1892, vicar-general of the diocese. Because of failing health, Bishop Hogan petitioned Rome for assistance and on June 29, 1896, Father Glennon was consecrated coadjutor bishop of Kansas City. Seven years later, on April 27, 1903, he was appointed coadjutor to Archbishop John Kain of St. Louis, a larger jurisdiction of approximately 32, 000 square miles and 225, 000 Roman Catholics. When Archbishop Kain died on October 13 of that same year, Glennon succeeded as archbishop, a position he held until his death. Glennon soon proved himself an able builder and administrator. On May 1, 1907, he broke ground for a new cathedral, the largest Roman Catholic church in North America at the time. He dedicated the new Kenrick Seminary in 1916 and the St. Louis Preparatory Seminary in 1931. Conservative in finance, he was a builder but not a borrower. In establishing new parishes, he anticipated population trends and the direction of suburban growth. In his long tenure, he erected ninety-five parishes, five hospitals, and almost a hundred schools. A traditionalist in education, he favored neither coeducation nor the attendance of Roman Catholic children in public schools. He centralized the administration of the parochial school system by establishing the office of Archdiocesan Superintendent of Schools in 1910. He was a supporter of The Catholic University of America, serving on its board of trustees for forty years, taking special interest in its library holdings, and initiating fund drives. Within his own archdiocese, he took a keen interest in St. Louis University, helped to organize the Catholic Historical Society of St. Louis, and was instrumental in the establishment of three colleges for women, Fontbonne, Webster, and Maryville College of the Sacred Heart. The problems of the poor and the immigrant were of special concern to him. He was a sponsor of the American Colonization Society and other efforts to settle Roman Catholic immigrant groups on farm lands in the Southwest, and he gave his warm support to Father Peter Dunne's Newsboys' Home and Protectorate, to Father Timothy Dempsey's Hotel for Homeless Men, and to other charities. He erected parishes and catechism centers for the black Roman Catholics of his archdiocese, but his successes in this area, like those of many of his fellow bishops in the early twentieth century, were limited. An outstanding orator, he was invited to preach on some of the most memorable occasions of the American Roman Catholic church, including the centenary of the Baltimore cathedral in 1906, the consecration of St. Patrick's Cathedral in New York in 1910, and the funeral service for Cardinal Gibbons in 1922. In. 1945, at the age of eighty-three, Glennon was named a cardinal by Pope Pius XII and invested with the robes of his new office on February 21, 1946, in Rome. While visiting Ireland before returning to St. Louis, he contracted pneumonia, followed by uremic poisoning, and died at the home of President Sean O'Kelly in Dublin. His body was returned to St. Louis on March 13, and he was buried in the crypt under Cathedral Basilica of Saint Louis, the cathedral he had built and of which he was so justly proud.
On public issues, Glennon was an opponent of both prohibition and the Child Labor Amendment. He had hoped that America could avoid World War I, but, when war was declared, he was one of the first to sign Cardinal Gibbons' resolution of support for President Wilson. Avoiding fanaticism, however, he refused to prohibit the use of German in his national parishes. An outspoken champion of Irish independence, he opposed Article X of the Treaty of Versailles because he feared it might perpetuate the existent division of Ireland.
Coadjutor Bishop of Kansas City (1896-1903), Archbishop of St. Louis (1903-1946)
Glennon was tall, erect, and dignified, yet never forgot his humble origins nor lost his ready sense of humor. He enjoyed sports, a good cigar, and informal visits with friends and neighbors.
