That this expectation is fully borne out by the facts is shown by the traffic map, figure 20. Here the 1940 traffic on existing roads closely conforming to the recommended system is compared with the traffic on other roads included in the numbered United States highway system. In examining this map it must be remembered that all of the roads represented have been selected from the total highway system many times as large, because of their special importance as traffic carriers. In other words, on this map the traffic of the recommended system is compared not with the general level of rural highway traffic, but with the traffic of other roads which themselves rank among the most heavily traveled highways in their respective sections of the country.
It will be observed at once that some heavily traveled sections of highway are not included: in the recommended system. It will be seen, however, that with few exceptions, the recommended routes are the most heavily traveled in their respective regions. In the exceptional cases the choice of the recommended route has been determined by the criterion of most direct connection between major cities. To include in the system all routes locally approximating the volume of traffic served by the recommended routes, would substantially increase the mileage of the system and generally result in a duplication of routes serving the same general areas and travel objectives.
In some instances traffic of the longer range is now divided between an existing road conforming most closely to the recommended interregional route and another parallel road of substantially equal directness and degree of improvement. There are also instances in which an existing road closely follows the recommended route, but because of a local inferiority in either directness or condition, carries a smaller traffic than an alternate road.
The committee wishes to emphasize that its recommendation applies to general routes and not to specific highways, notwithstanding the fact that the various maps presented in this report show the recommended routes as following the general location of selected existing highways.
In a detailed location of the routes of the system, the exact location at all points will be a problem for local reconnaissance study. The eventual final selection of line may, therefore, more closely approximate existing roads other than those followed in the general-system maps herein presented. To a considerable extent the proper development of the recommended system will result in the location of the recommended routes, locally, on new lines conforming to no existing highway.
The comparison made possible by figure 20 is therefore to be considered as only a very general one.
Of the 29,450 miles of rural. roads approximating the location of rural sections of the recommended system, traffic counts made by the highway planning surveys in 1941 show that 6,056 miles, or 20.6 percent of the total, carried traffic that year averaging less than 1,000 vehicles daily. On 9,576 miles, or 32.5 percent, the daily traffic averaged between 1,000 and 2,000 vehicles. A total of 6,10 miles, or 20.7 percent, served traffic averaging between 2,000 and 3,000 vehicles daily; 7,182 miles, or 24.4 percent, carried traffic between 3,000 and 10,000 vehicles per day; and only 532 miles, or less than 2 percent of the total, carried an average daily traffic of
