ELEC §21506: (a) The term of office of any supervisor who has been elected and whose term of office has not expired shall not be affected by any change in the boundaries of the district from which the supervisor w

(a) The term of office of any supervisor who has been elected and whose term of office has not expired shall not be affected by any change in the boundaries of the district from which the supervisor was elected and that supervisor shall continue to represent the constituents residing in the district boundaries from which the supervisor was elected for the duration of that term of office. This section does not prevent a board from assigning a county elected official or county official to provide constituent services for residents of an area that is temporarily not represented by a supervisor due to redistricting. (b) At the first election for county supervisors in each county following adoption of the boundaries of supervisorial districts, excluding a special election to fill a vacancy or a recall election, a supervisor shall be elected for each district under the new district plan that has the same district number as a district whose incumbent’s term is due to expire. This subdivision does not apply when a county transitions from at-large to district-based elections. (c) For a county employing both a primary and a general election, a change in the boundaries of a supervisorial district shall not be made between the direct primary election and the general election. (d) Except as provided in subdivision (a), a person is not eligible to hold office as a member of a board of supervisors unless that person meets the requirements of Section 201 of the Elections Code and Section 24001 of the Government Code.