W. Va. Code § 7-1-3I

Any county commission may join together in the exercise of any of its powers, duties and responsibilities, or otherwise cooperate with any other county or counties, municipality or municipalities, the government of this state or of the United States in carrying out any lawful purpose not in conflict with the Constitution of West Virginia: Provided, That the county commission of any county sharing a common border with any other state is hereby empowered to enter into reciprocal agreements with governmental subdivisions or agencies of such other state for the protection of people and property from fire and for emergency medical services and for the reciprocal use of county equipment and personnel for such purpose.