On April 3, 1914, Curley was appointed the fourth Bishop of St. Augustine by Pope Pius X. He received his episcopal consecration on the following June 30 from Bishop Benjamin Joseph Keiley, with Bishops Patrick James Donahue and Owen Corrigan serving as co-consecrators. At the age of 34, Curley was the youngest member of the American hierarchy. He would spend eight months out of every year on journeys throughout the diocese, and by the end of his tenure, the Catholic population had grown from 39,000 to 41,000, with 40 new churches built. During the 1910s, anti-Catholicism was on the rise in Florida. Curley attracted national attention by battling thar prejudice in the legislature, which made an unsuccessful attempt to pass a convent-inspection bill. However, the legislature passed legislation that prohibited white women from teaching black children. Curley refused to comply with the law, and three Sisters of St. Joseph were subsequently arrested. He led a campaign to have the law declared unconstitutional, which eventually occurred. He also sought to educate Floridians about Catholicism and demonstrate the bigotry of the Ku Klux Klan. During World War I, Curley was a strong supporter of the war effort. In 1917, he established the Diocesan Catholic War Council, a group that gave spiritual guidance to Florida's Catholic soldiers heading off to war. He spoke at Liberty Bond rallies and, at the end of the war, celebrated the largest memorial Mass for fallen Allied soldiers at Battery Park in New York City.
Baltimore
On August 10, 1921, Curley was appointed the tenth Archbishop of Baltimore, Maryland, by Pope Benedict XV. His installation took place on the following November 30. His arrival in his new city was described as "one of the greatest welcomes ever tendered a new citizen of Baltimore." During his tenure in Baltimore, Curley distinguished himself as an advocate for education. He established 66 schools in 18 years, placing the importance of constructing schools over churches. In 1926, he declared, "I defy any system of grammar schooleducation in the United States to prove itself superior to the system that is being maintained in the Archdiocese of Baltimore." He also established diocesan offices for Catholic Charities and for the Society for the Propagation of the Faith. Outspoken on political and social affairs, Curley was a strong opponent of the foreign policy of President Franklin Roosevelt, anticlerical governments of Mexico and Spain, the American film industry, and the establishment of Newman Centres at secular universities, which he felt undermined Catholic schools. In 1936, he called upon his fellow Catholic bishops to conduct a study of the influences of communism in the United States. He once engaged in a public feud with The Baltimore Sun when one of its reporters compared Adolf Hitler to Ignatius of Loyola. Although his predecessor, the legendary James Gibbons, was a cardinal, Curley never received the same distinction.
Baltimore-Washington
On July 22, 1939, Pope Pius XII separated Washington, DC, from the Archdiocese of Baltimore to form the new Archdiocese of Washington. While retaining his position as Archbishop of Baltimore, Curley was named the first Archbishop of Washington and governed the two archdioceses as a single unit. His later years were burdened with progressive blindness and failing health. He died from a stroke at 66 and was buried in the Basilica of the Assumption in Baltimore. After his death, separate archbishops were appointed for Baltimore and Washington.
