That portion of K-161 highway from the junction of K-161 highway with United States highway 36, north on K-161 highway to the Nebraska state line is hereby designated as the ancient Indian traders trail. The secretary of transportation shall place highway signs along the highway right-of-way at proper intervals to indicate that the highway is the ancient Indian traders trail, except that such signs shall not be placed until the secretary has received sufficient moneys from gifts and donations to reimburse the secretary for the cost of placing such signs and an additional 50% of the initial cost to defray future maintenance or replacement costs of such signs. The secretary of transportation may accept and administer gifts and donations to aid in obtaining and installing suitable signs.