Okla. Stat. tit. 69, § 69-1674: Mannford Expressway

State Highway 51, from a point one mile east of its intersection

with State Highway 151, also known as the “Keystone Dam Road”, west

to its intersection with State Highway 48 in Mannford, Oklahoma,

shall be designated as the “Mannford Expressway”. The Department of

Transportation shall cause suitable permanent markers to be placed

upon the highway bearing the designation.