▁on ▁the ▁north ▁end ▁through ▁K alk aska ▁ceased ▁to ▁be ▁considered ▁in ▁ 2 0 0 0 . ▁South ▁of ▁Three ▁R ivers , ▁MD OT ▁is ▁studying ▁possible ▁up gr ades ▁to ▁US   1 3 1 . ▁One ▁option ▁for ▁these ▁up gr ades ▁is ▁a ▁full ▁fre ew ay , ▁an ▁option ▁that ▁was ▁initially ▁rejected . ▁The ▁preferred ▁alternative ▁in ▁ 2 0 0 8 ▁was ▁a ▁two - lane ▁by pass ▁of ▁Const antine ▁that ▁opened ▁in ▁October ▁ 2 0 1 3 . ▁ ▁Route ▁description ▁Running ▁ ▁in ▁Indiana ▁and ▁Michigan , ▁US   1 3 1 ▁in ▁its ▁entire ty ▁is ▁listed ▁as ▁a ▁part ▁of ▁the ▁National ▁Highway ▁System , ▁a ▁system ▁of ▁roads ▁cru cial ▁to ▁the ▁nation ' s ▁economy , ▁defense ▁and ▁mob ility . ▁As ▁a ▁state ▁highway ▁in ▁both ▁states , ▁the ▁road way ▁is ▁maintained ▁by ▁the ▁Indiana ▁Department ▁of ▁Transport ation ▁( IND OT ) ▁and ▁MD OT . ▁The ▁Michigan ▁section ▁includes ▁approximately ▁ ▁of ▁fre ew ay ▁between ▁Kal am az oo ▁and ▁W ex ford ▁count ies . ▁ ▁Indiana ▁US   1 3 1 ▁extends ▁ ▁through ▁El kh art ▁County , ▁Indiana , ▁between ▁the ▁entrance ▁to ▁the ▁Indiana ▁T oll ▁Road , ▁a ▁few ▁hundred ▁feet ▁north ▁of ▁the ▁T oll ▁Road ▁over pass , ▁and ▁the ▁state ▁line ▁to ▁the ▁north . ▁State ▁Road ▁ 1 3 ▁( SR   1 3 ) ▁runs ▁concurrent ly ▁with ▁US  