Where do we find a case in which an animal renders an entire city impure?

This Torah study examines the question: Where do we find a case in which an animal renders an entire city impure? The canonical Hebrew discussion develops the issue through the weekly Torah portion and the sources cited there, preserving the distinctions, tensions and practical implications that belong to the source itself. This localized layer is designed for study and discovery; it does not add a new halakhic, medical, legal, historical or empirical ruling beyond the canonical Hebrew source.