The county board of each county shall select and designate, within six months from January 1, 1958, the roads which will be county primary roads and which will constitute the county primary road system. Such roads shall be selected from those roads which already have been designated as primary county roads pursuant to section 39-2001 or from those roads which were maintained by the Department of Transportation under section 39-1309. The primary county roads shall include only the more important county roads as determined by the actual or potential traffic volumes and other traffic survey data.

The county board of each county shall have authority to redesignate the county primary roads from time to time by naming additional roads as primary roads and by rescinding the designation of existing county primary roads. The county board shall follow the same procedure for redesignation as is required by law for initially designating the county primary roads. The principle of designating only the more important county roads as primary roads as determined by the actual or potential traffic volumes and other traffic survey data shall be adhered to.

A copy of a current map of the county roads showing the location of roads and bridges and reflecting the county primary road system as designated in this section shall be kept on file and available to public inspection at the office of the county clerk and with the department.