Virginia constitution
Article VII: local government
Section 3

The General Assembly may provide by general law or special act that any county, city, town, or other unit of government may exercise any of its powers or perform any of its functions and may participate in the financing thereof jointly or in cooperation with the Commonwealth or any other unit of government within or without the Commonwealth. The General Assembly may provide by general law or special act for transfer to or sharing with a regional government of any services, functions, and related facilities of any county, city, town, or other unit of government within the boundaries of such regional government.