(a) The commission shall divide the state into not more than 25 districts for the purpose of the performance of the department’s duties.
(b) In determining a district’s boundaries, the commission shall consider all costs and benefits, including highway activity in and the number of employees required for the proposed district.

(c) Not more than one district office may be in a district.
(d) The commission shall determine the number of department offices necessary for maintenance and construction personnel in a district.
(e) The commission periodically shall review the necessity for the number of maintenance, construction, and support operations in each district. The commission shall include the findings of its review as a part of the department’s budget request submitted to the Legislative Budget Board.
(f) The department is exempt from any law purporting to require the department to conform the provision of its services to service regions other than the districts established under this section.
(g) The commission may require by rule that any product or material that is approved for use in any one district may be approved for use by any other district.
(h) The commission by rule shall prescribe criteria for the classification of each district as metropolitan, urban, or rural. The rules must classify a district with a population of more than one million as metropolitan.