http://www.fhwa.dot.gov/infrastructure/longest.cfm Highway 20 was commissioned as an official route Highway 20 was commissioned as an official route confirms Highway 20 was commissioned as an official route the longest highway in the U.S. longest road Highway 20 was commissioned as an official route Highway 20 was commissioned as an official route Highway 20 was commissioned as an official route confirms Highway 20 was commissioned as an official route Highway History http://www.fhwa.dot.gov/infrastructure/longest.cfm Highway 20 was commissioned as an official route