Iowa Code § 524.601: Board of directors.

1. The business and affairs of a state bank shall be managed by a board of five or more directors eighteen years of age or older, a majority of whom shall be residents of the state of Iowa and citizens of the United States.

2. The number of directors may be increased, or decreased to a number not less than five, by the shareholders at the annual meeting, or at a special meeting called for that purpose, but no decrease shall have the effect of shortening the term of an incumbent director.