(1)    The department shall designate and, subject to sub. (2), mark the entire route of USH 63 as the “Gaylord Nelson Highway” in recognition and appreciation of Gaylord Nelson, the native son of Clear Lake who served with distinction as both the governor from 1959 to 1963 and a U.S. senator from 1963 to 1981, and whose legacy includes numerous environmental achievements, including the founding of Earth Day, the creation of the Knowles-Nelson Stewardship Program, and the preservation of the Apostle Islands in Lake Superior.

   (2)   Upon receipt of sufficient contributions from interested parties, including any county, city, village, or town, to cover the costs of erecting and maintaining markers along the route specified in sub. (1) to clearly identify to motorists the designation of the route as the “Gaylord Nelson Highway,” the department shall erect and maintain the markers. No state funds, other than from the receipt of contributions under this subsection, may be expended for the erection or maintenance of the markers.