Ark. Code Ann. § 14-37-113

Whenever any law of this state provides that the provisions of it shall apply to any city within a defined population classification, it is declared to be the intent of the General Assembly that, in the event any city to which the law was applicable at the time of the enactment of that law shall subsequently achieve a lesser or greater population than the classification prescribed by law, the law shall nevertheless thereafter be equally applicable to any such city, irrespective of the fact that the city no longer has a population within the classification prescribed by the law.