The control of each Reserve bank is vested in a board of directors composed of nine members. This board is divided into three classes, of three members each, designated as classes A, B, and C. The class C directors are appointed by the Federal Reserve Board and one of these class C directors is designated by the Federal Reserve Board as chairman of the board of directors of the bank and as Federal Reserve agent. The other six members known as class A and class B directors are elected by the member banks of the district. For the purpose of selecting these six directors the member banks of each district are divided into three divisions or groups. The reason for this division is to assure the banks with a small and medium sized capital a voice in the control of the Federal Reserve bank. Thus in electing directors the smallest member bank has a single vote, the same as the largest member bank. Each division or group chooses one class A and one class B director. Three of the six, or class A directors, must be bankers, and the other three, or class B directors, must represent the industrial, commercial and agricultural interests of the district. Such board of directors shall hold office for equal terms of three years each, but these terms are so arranged that two directors retire each year, thus affording an opportunity for rotation in office.