Kær was formerly part of the German Empire. In the German Empire, the place was called Kjär.
The place is now called Kær (Sønderborg-Kær) and belongs to Denmark.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Kjär | German Empire | Sonderburg | before the Versailles Treaty |
| Kær | Denmark | Sønderborg | after the Versailles Treaty |
| Kær (Sønderborg-Kær) | Denmark | Sønderjylland | 1993 |