. ▁ ▁The ▁highway ' s ▁western ▁termin us ▁is ▁in ▁Aber de en , ▁Washington , ▁at ▁an ▁intersection ▁with ▁US ▁ 1 0 1 , ▁while ▁the ▁highway ' s ▁eastern ▁termin us ▁is ▁in ▁Dow nt own ▁Detroit , ▁at ▁the ▁corner ▁of ▁Michigan ▁and ▁Cass ▁a ven ues , ▁near ▁Camp us ▁Mart ius ▁Park . ▁ ▁Route ▁description ▁ ▁Washington ▁ ▁The ▁western ▁termin us ▁of ▁US ▁ 1 2 ▁is ▁located ▁in ▁Aber de en , ▁Washington . ▁ ▁In ▁the ▁ 1 9 6 0 s , ▁a ▁portion ▁of ▁US ▁ 1 2 ▁was ▁moved ▁north ▁to ▁the ▁town ▁of ▁Mort on , ▁when ▁the ▁M oss y rock ▁Dam ▁was ▁built ▁and ▁flo oded ▁the ▁towns ▁of ▁Kos mos ▁and ▁R iffe , ▁along ▁the ▁Cow l itz ▁River ▁in ▁Lewis ▁County . ▁ ▁A ▁large ▁portion ▁of ▁old , ▁two - lane ▁US ▁ 1 2 ▁was ▁replaced ▁by ▁Inter state ▁ 8 2 ▁and ▁Inter state ▁ 1 8 2 ▁in ▁the ▁ 1 9 8 0 s , ▁between ▁Y ak ima ▁and ▁the ▁Tri - C ities , ▁though ▁the ▁fre ew ays ▁are ▁still ▁cos igned ▁with ▁the ▁US ▁ 1 2 ▁design ation . ▁ ▁The ▁old ▁two - lane ▁highway ▁now ▁be ars ▁the ▁name ▁W ine ▁Country ▁Road . ▁ ▁The ▁highway ▁lo os ely ▁follows ▁the ▁east bound ▁leg ▁of ▁the ▁Lewis ▁and ▁Clark ▁Ex ped ition , ▁between ▁Wall ula , ▁Washington ▁and ▁Clark