(a) The portion of State Highway 21 in Nacogdoches County between County Road 713 and County Road 782 is designated as the Sergeant Tom Sitton Memorial Highway.
(b) Subject to § 225.021(c), the department shall:
(1) design and construct markers indicating the designation as the Sergeant Tom Sitton Memorial Highway and any other appropriate information; and
(2) erect a marker at each end of the highway and at appropriate intermediate sites along the highway.