 Every year the Washington State Department of Transportation ( WSDOT ) conducts a series of surveys on its highways in the state to measure traffic volume . This is expressed in terms of average annual daily traffic ( AADT ) , which is a measure of traffic volume for any average day of the year . In 2009 , WSDOT calculated that as few as 1 @,@ 100 cars traveled through the intersection with Bus Road just west of the Sunnyside Wildlife Recreation Area , and as many as 10 @,@ 000 cars passed through the town of Toppenish before the interchange with US 97 . 
