| 12 August 1911 | Territory Lost | Diocese of Davenport (Harrison, Polk, Warren, Clarke, Binggold, Shelby, Gass, Mills, Lucas, Decatur, Audubon, Pottawattamie, Montgomery, Fremont, Wayne, Guthrie, Adair, Adams, Page, Dallas, Madison, Union, and Taylor)
| Diocese of Des Moines (erected)
|