Thta's interesting about the Interstate Highway System. I was driving before the Interstate was completed. If you were going any distance, you had to drive through the downtown of every city or small town. I remember my Dad had shortcuts that avoided downtown of most of the cities we had to regularly drive through. Route 40, which was replaced by I-70 was mostly 2 lanes. Sometimes there was a passing lane going up hills. I remember 1st or 2nd gear following trucks up hills.