One of the last two - lane U.S. highways constructed , it was completed in the early 1960s , connecting Lewiston with Missoula over Lolo Pass .
Route 12 follows the Lochsa River along its north bank .
One of the last two - lane U.S. highways constructed , Lochsa River was completed in the early 1960s , connecting Lewiston with Missoula over Lolo Pass .
Route 12 follows the Lochsa River along its north bank .