Comprises that part of Iowa north of Polk, Jasper, Poweshiek, Iowa, Johnson, Cedar, and Clinton counties, and east of Kossuth, Humboldt, Webster, and Boone counties; area, 17,404 square miles; diocese established, 1837, erected into archdiocese, 1893; suffragans: Cheyenne, Davenport, Des Moines, Grand Island, Lincoln, Omaha, and Sioux City.