It extends 13.64 miles (21.95 km) from SR 7 in the census-designated place (CDP) of Elbe east to the Longmire gate of Mount Rainier National Park.

After passing Park Junction, SR 706 turns due east to National, where the railroad ends.

In Ashford, the highway returns going due east before starting to curve and then end at the entrance to Mount Rainier National Park.

[13] In 1901, residents of towns near the new national park lobbied the Pierce County government to construct a modern road to Longmire and later Paradise Valley.

[18] PSH 5 TR became SR 706 in 1964 during the 1964 highway renumbering, in which the Washington State Department of Transportation (WSDOT) replaced the previous system of Primary and Secondary Highways with a new system called State Routes, which is still in use today.