The Diocese of Kansas City-St. Joseph is a Roman Catholic diocese located in western Missouri, United States. Established on July 13, 1880, it covers an area of approximately 20,479 square miles with its territorial see at the Cathedral of the Immaculate Conception in Kansas City, Missouri. The Diocese serves around 196,000 Catholics and is led by a bishop who oversees the spiritual needs of the faithful and pastoral activities within the diocese. The Diocese of Kansas City-St. Joseph is part of the ecclesiastical province of Kansas City in the Roman Catholic Church in the United States.