  1 3 1 ▁ran ▁directly ▁south ▁of ▁White ▁P ige on ▁to ▁the ▁state ▁line . ▁In ▁the ▁process , ▁the ▁M - 1 0 3 ▁design ation ▁was ▁sw apped ▁with ▁US   1 3 1 . ▁ ▁The ▁M SH D ▁had ▁proposed ▁that ▁the ▁section ▁of ▁US   1 3 1 ▁south ▁of ▁Kal am az oo ▁be ▁built ▁as ▁an ▁electronic ▁highway ▁under ▁a ▁bid ▁through ▁General ▁Mot ors ▁the ▁same ▁year ; ▁the ▁testing ▁for ▁such ▁a ▁road way ▁was ▁ultimately ▁done ▁at ▁Ohio ▁State ▁University ▁instead . ▁Another ▁project , ▁through ▁the ▁end ▁of ▁ 1 9 6 1 , ▁extended ▁the ▁fre ew ay ▁south ▁to ▁P lain well ▁and ▁north ▁into ▁dow nt own ▁Grand ▁Rap ids . ▁This ▁extension ▁was ▁designated ▁as ▁part ▁of ▁Bus . ▁US   1 3 1 ▁and ▁opened ▁in ▁December ▁ 1 9 6 1 . ▁The ▁opening ▁ceremony ▁for ▁the ▁bridge ▁across ▁the ▁Grand ▁River ▁included ▁the ▁state ▁highway ▁commission ▁and ▁the ▁then - Miss ▁Michigan , ▁pulled ▁by ▁a ▁team ▁of ▁s led ▁dogs , ▁to ▁lead ▁the ▁first ▁traffic ▁over ▁the ▁river . ▁ ▁Until ▁the ▁early ▁ 1 9 6 0 s , ▁US   1 3 1 ▁never ▁left ▁the ▁state ▁of ▁Michigan ; ▁the ▁southern most ▁point ▁was ▁always ▁at ▁the ▁Indiana ▁state ▁line . ▁In ▁ 1 9 6 1 , ▁the ▁highway ▁design ation ▁was ▁extended ▁to ▁its ▁current ▁southern ▁termin us ▁in ▁rural ▁El kh art ▁County , ▁Indiana