Miscellaneous =The Highway System Unit.=--Ordinarily the units will be the same as the political divisions, that is, national, state, or local. A national system would include the whole United States and will comprise trunk lines paralleling each other across the country east and west and north and south, considering, of course, ruling points, with a few branch lines of importance. The total number of miles of such highways should probably never exceed 2 per cent of the total mileage in the United States, or about 50,000 miles. A national highway committee estimated that this mileage of roads would serve 87 per cent of the people. The arguments made in favor of a national system of highways may be briefly summarized as follows: (1) Political lines would be obliterated, thus welding together and unifying all the people. Commercial and social intercourse would wipe out sectional differences, hatreds, and enmities. The people of one section would learn that the people of another section are human beings as they themselves are, and are actuated by the same instincts and inspirations. (2) Economic, commercial, and pleasure routes cut across state lines and it would be much better to have the roads continuous and administered by one central control. They would then be kept in a more uniform condition of usefulness. The roads radiating from New York City are mentioned as an example. They pass out of the state of New York and into the states of Connecticut, Rhode Island, Massachusetts, New Jersey, Pennsylvania, Delaware, Maryland, and the District of Columbia. On any one of these roads it would be difficult to say which state you are in by observing the license tags on the trucks and automobiles. A Connecticut traffic census on a road carrying approximately 3000 passenger cars and 500 trucks per day showed that 47 per cent of the cars in the analysis came from without the state. (3) Military. All roads would become military during war. It is frequently stated that the good roads of France saved Paris from invasion and probably saved the war to the allies. The German General Kluck admits that while he was advancing upon the British and French south of the Marne, an army of which he had no suspicion had struck outward from Paris and put his flank in deadly peril.[176] This army was one that Joffre had concentrated in Paris under General Maunouri, which had been brought over two or three good French roads from Paris by motor trucks and lorries to a point within striking distance of the German right flank, where he attacked and began the First Battle of the Marne. In the Second Battle of the Marne, motor cars performed a very important part in the concentration of troops which were to make a surprise attack. In addition the motorized armed cars known as tanks played an important part.