August 20 , 1999 , the section east of Roosevelt Dam was renumbered as SR 188 , cutting SR 88 back to its current terminus .
The extra designations at SR 88 's western terminus were removed by 1971 , leaving only the US 60 designation .
August 20 , 1999 , the section east of Roosevelt Dam was renumbered as SR 188 , cutting SR 88 back to SR 88 's current terminus .
The extra designations at SR 88 's western terminus were removed by 1971 , leaving only the US 60 designation .