Idaho Code § 33-1502
The board of trustees of each school district may establish, and alter, bus routes and establish, and alter, non-transportation zones. Such routes and zones shall be determined for each year not later than the regular August meeting of the board; but nothing herein shall be construed as limiting the board in altering such routes or zones when change in the condition of the roads, or in the number of pupils being transported would justify such alteration.
A non-transportation zone shall comprise an area of a school district designated by the board of trustees which is impracticable, by reason of sparsity of pupils, remoteness, or condition of roads, to serve by established bus routes.
Whenever practicable, routes shall be so established that no bus stop shall be more than one and one-half (1 1/2) miles from the intersection of the driveway of the home of any pupil otherwise eligible for transportation and the nearest public road; except that no board of trustees shall be required to route school buses or other passenger equipment over any road not maintained as a part of a highway district, county, state or federal highway system, or by the state or national forest service; except, that the primary requirements to be observed by the board of trustees are the safety and adequate protection of the health of the pupils.
Idaho Code § 33-1502