The longest road in the world that can be travelled in a motor vehicle is the pAN-AMERICAN Highway. The highway is in fact a system of roads that extends from the u.s.- Mexican border to southern chile. It also connects the east and west coasts of south america, and links the capitals of 17 latin- american countries. The 47,516 km system benifits latin americas economy. The highways is sometimes described as running through the western united states and canada up into alaska, but neither country has officially named any highway as part of the Pan- American highway system.:)