. ♪ narrator: once in a while, a car , as ifalk at the furnace in an effort to save itself, the modelcene, the emphasis and new direction he gave to our way of life did not stop there. that carriedmentum y 1920's. gat ♪ even the grim depression of the 30's could not stop the powerful forces that had been set into motion. ♪ narrator: the lessons learned from the assembly line in mass production helped us to win a long and terrible war. ♪ narrator: nothing has been able to stop it. , andve kept on working today, this is how the american road looks. the whole nation has become mobile, flowing along over a great network of highways, more than 3 million miles long and constantly growing. the american road has lifted itself high above the muddy ruts of 50 years ago. ♪ has bridgede road the gap between city and country , their ways of life have mingled and both share the fruits of progress equally. machines have taken the burden of the work from the back of the , no longer do the women on the farms grow old before their time. and the people of the cities have been able to move out to quite c