SR331 first appeared on the February 1933 edition of the Indiana State Highway Commission map of the state highway system, running from SR25 in the south to SR2 (later US33 then SR933) in the north.[4] By 1953 it had been extended northward to US20 (later BusinessUS20).[5][6] Between 1980 and 1987 SR331 was routed east of downtown Mishawaka.[citation needed] In June 1999 it was relocated eastward north of the St. Joseph Valley Parkway (US20) in anticipation of a highway upgrade there which had been completed in part.[7] Although by law the entire project was to have been completed by January 1, 2009,[3] in reality it was finished by September 30, 2013.[8][9] Subsequently, in August 2014 the Indiana Department of Transportation relinquished the parallel portions of the route which it had acquired in 1999.[10]
12Indiana Department of Transportation (July 2016). Reference Post Book(PDF). Indianapolis: Indiana Department of Transportation. Retrieved February 3, 2017.
↑Indiana State Highway Commission (February 1933). State Highway System of Indiana (Map). 1:618,000. Indiana State Highway Commission. §B6. OCLC53355434. Retrieved September 7, 2018– via Indiana State Library and Historical Bureau.
↑Indiana State Highway Commission (1952). State Highway System of Indiana (Map). 1:660,000. Indiana State Highway Commission. §B7. OCLC55533635. Retrieved September 7, 2018– via Indiana State Library and Historical Bureau.
↑Indiana State Highway Department (1953). State Highway System of Indiana (Map). 1:660,000. Indiana State Highway Department. §B7. OCLC64574685. Retrieved September 7, 2018– via Indiana State Library and Historical Bureau.
↑Staff (May 20, 1999). "Signs to Mark Elm, Capital as Indiana 331". South Bend Tribune. p.D2.
