=County Administration.=--In some states the county is the smallest administrative unit in the road system. A county board, called the board of county supervisors or board of county commissioners consisting of from three to fifteen members, is the administrative authority. Its members are elected for fixed terms which vary in length from one to five years. The county board usually has many public responsibilities other than highway administration, and is generally made up of men with considerably more business ability than the average township board. The county board has jurisdiction over all of the highways in the county in some states, and in others it has charge of only the more important highways. In most states, the laws set forth specifically what highways shall be under the jurisdiction of the county authorities. In addition to having direct supervision of the improvement and maintenance of the roads assigned to county administration, the county boards in some states arrange for the construction of all culverts and bridges on the roads that are under township supervision, or at least the more expensive bridges and culverts on such roads. Sometimes this is accomplished by granting county aid for township bridges, under which system the county pays a part of the cost of the construction of bridges on the township roads. The amount of aid varies, but is generally about one-half of the cost, and the township and county officials jointly assume the responsibility of arranging for the construction by contract or otherwise. The county board obtains funds for road work through a direct tax on all property in the county, the maximum rate being limited by statute. County boards are also authorized to issue bonds for road construction under statutory restrictions and limitations similar to those effective in the township as to total amount issued, and many millions of dollars' worth of highway bonds have been issued by county authorities in the United States. =State Administration.=--In a state, the administrative authority in highway matters is vested in a board of commissioners usually consisting of three or more members. In a few states, the administrative authority is delegated to a single commissioner. Where the authority is vested in a board, that board is usually appointed by the governor. In several states one or more members of the commission hold that position _ex officio_; for example, in several states the governor is by law a member of the commission, in others the secretary of state or the dean of engineering at the State University or the state geologist is a member of the commission. Where the administrative authority is a single commissioner he may be elected along with other state officers, but this is the case in only a few states.