Ustków was formerly part of the German Empire. In the German Empire, the place was called Sassenstein.
The place is now called Ustków and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Ustkow | German Empire | Krotoschin | before the Versailles Treaty |
| Ustków | Poland | Krotoszyn | after the Versailles Treaty |
| Sassenstein | German Empire | Krotoschin | 1939 |
| Ustków | Poland | Krotoszyn | 1945 |
| Ustków | Poland | Kalisz | 1992 |