Why is it der Badener?

Badener ends in -er, and most nouns ending in -er are masculine: in a German dictionary, 86% of them take der.

All nouns ending in -er
Sense 1
der

Meaning

[1] regarding the Baden region, belonging to it, from it

[1] die Region Baden betreffend, zu ihr gehörend, aus ihr stammend

Examples

[1]

[1]

Declension

Positiv Komparativ Superlativ
Badener — —

Pronunciation

Dictionary entries include material from Wiktionary. Wiktionary