The Diocese of Lansing, originally comprised of 15 Southern Michigan counties, was established by Pope Pius XI by proclamation dated May 22, 1937. Previously, these counties had been part of the Archdiocese of Detroit and the Diocese of Grand Rapids. In May 1938 with the establishment of the Diocese of Saginaw, the counties of Allegan, Barry and Ionia were annexed from the Diocese of Lansing to the Diocese of Grand Rapids, and the counties of Genesee, Livingston and Shiawassee were annexed from the Archdiocese of Detroit to the Diocese of Lansing. In July 1971 from the Dioceses of Lansing, Grand Rapid and Saginaw, the Dioceses of Kalamazoo and Gaylord were formed. At that time, Washtenaw and Lenawee Counties were annexed to the Diocese of Lansing from the Archdiocese of Detroit.The Diocese of Lansing is currently comprised of 10 counties covering 6,218 square miles: Clinton, Eaton, Genesee, Hillsdale, Ingham, Jackson, Lenawee, Livingston, Shiawassee and Washtenaw counties. Major cities are Lansing, Adrian, Ann Arbor, Flint, Jackson, Owosso and Ypsilanti. 2013 figures provided by the U.S. Census Bureau estimate the total population in the 10 county area at 1,795,538. The Official Catholic Directory 2014 approximates the diocesan Catholic population at 195,858.