Alabama constitution
Article IX: representation
Section 200

It shall be the duty of the legislature at its first session after taking of the decennial census of the United States in the year nineteen hundred and ten, and after each subsequent decennial census, to fix by law the number of senators, and to divide the state into as many senatorial districts as there are senators, which districts shall be as nearly equal to each other in the number of inhabitants as may be, and each shall be entitled to one senator, and no more; and such districts, when formed, shall not be changed until the next apportioning session of the legislature, after the next decennial census of the United States shall have been taken; provided, that counties created after the next preceding apportioning session of the legislature may be attached to senatorial districts. No county shall be divided between two districts, and no district shall be made up of two or more counties not contiguous to each other.