ic highways are therefore national in scope. This fact
has been recognized in Europe, notably in England, France and Belgium,
where the public highways are administered largely as national
utilities.

Until recent years, highway improvement in the United States has been
subordinated to other more pressing public improvements, but during
the World War the inadequacy of the transportation system of the
United States became apparent. While such an unprecedented load upon
transportation facilities may not recur for many years, it has become
apparent that more rapid progress in highway improvement is necessary
and in the United States the subject is now likely to receive
attention commensurate with its importance.

=Development of Traffic.=--The character and extent of the highway
improvement needed in any locality is dependent entirely on the
demands of traffic. In sparsely settled areas, particularly those that
are semi-arid or arid, the amount of traffic on local roads is likely
to be small and the unimproved trails or natural roads adequate. But
as an area develops either on account of agricultural progress or the
establishment of industrial enterprises, the use of the public
highways both for business and for pleasure increases and the old
trails are gradually improved to meet, at least to some degree, the
new demands of traffic. In sparsely settled areas, it is possible for
the public to accommodate its use of the highways to the physical
condition thereof, and business is more or less regulated according to
the condition of the roads. This is not always pleasant or economical
but is the only possible arrangement. In populous districts, with
diversified activities, it becomes imperative to have year-round
usable roads in order to transact with reasonable dispatch the regular
business of the industries. Anything less will handicap normal
community progress.

The advent of the motor driven vehicle in the United States has
resulted in a greatly increased use of the public highways of
agricultural areas, even of those that are sparsely populated, because
of the convenience of the motor vehicle both for passenger and for
freight service. Probably in excess of 90 per cent of the tonnage
passing over the rural highways in the United States is carried by
motor vehicles. This class of traffic has really just developed and no
one can predict what it will be in ten years, yet it has already
introduced into the highway problem