English: Section of the Official Highway Map from October 1, 1957, showing the routing of US 223 and M-151 in Michigan
Date
Source
Michigan State Highway Department (October 1, 1957). Official Highway Map (Map). [c. 1:918,720]. Lansing: Michigan State Highway Department. §§ N11–N13. OCLC12701120 and 367386492.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.