Interstate highway 670 where it enters the state on the Kansas-Missouri line on the east, thence west to the junction with Interstate highway 70, is hereby designated as the Dillingham freeway. The secretary of transportation shall place markers along the highway right-of-way at proper intervals to indicate that the highway is the Dillingham freeway. The secretary of transportation may accept and administer gifts and donations to aid in obtaining and installing suitable highway signs bearing the proper approved inscription.