Well it appears that since new territories have been created and inhabited it appears that new motorways have also been laid out. It appears that recently granted territories have motorways been mapped on them before any natural feature or even a mere surface route.
I don't understand what the infatuation with a motorway is anyway. They are expensive to build, take up valuable real estate and they also contribute to blight and sprawl. Having said that I know that they are a necessity in a country that needs to move goods and services.