Ala. Code § 11-85-71
The respective regional planning and development commissions ratified and confirmed by Section 11-85-70 shall henceforth continue to act and operate as regional planning and development commissions within their respective districts, and any governmental units within a particular district desiring to become a member of, and have representation on a commission within the district in which the governmental unit is located, shall pass resolutions or ordinances as applicable to accomplish that purpose and they shall thereupon become members of the commission within their respective district and shall be granted the respective representation on the commission as is provided by Section 11-85-53, provided they agree by appropriate resolution or ordinance, as applicable, to contribute to the financing of the commission in keeping with a formula of financing on a population basis in the same proportion as current members as established by the commission.
Ala. Code § 11-85-71 (1975)