Routing changes and proposals US 12 was proposed to enter Wyoming on the current route of US 212 from Mammoth Hot Springs to a point northwest of Clark before its route in Montana was rerouted. It was also proposed to enter Oregon on the current route of US 730 from east-southeast of Boardman to a point northeast of Cold Springs, but that was canceled.
routing chANGes and proPosals us 12 Was PRopoSed to entEr wyoMiNg On the currENT Route of US 212 from mAmmOth hot SPRings TO a point nortHwESt of claRK Before ITS ROUtE iN montANa WaS rerouted iT wAS AlSo PrOposEd To enteR Oregon oN THe curreNT ROuTe oF Us 730 froM eAst-souTHeasT of boardman TO a Point northEasT of ColD sPrINgs but thAt was caNceLed