Interstate highway 635 where it enters the state on the Kansas-Missouri line on the north, thence south to the junction with Interstate highway 35, is hereby designated as the Harry Darby memorial highway. The secretary of transportation shall place markers along the highway right-of-way at proper intervals to indicate that the highway is the Harry Darby memorial highway. 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.