n he recites the following
facts: "In Arizona, approximately 93% of the freight traffic and 95% of
the passenger traffic is interstate. Because of the Train Limit Law
appellant is required to haul over 30% more trains in Arizona than would
otherwise have been necessary. The record shows a definite relationship
between operating costs and the length of trains, the increase in length
resulting in a reduction of operating costs per car. The additional cost
of operation of trains complying with the Train Limit Law in Arizona
amounts for the two railroads traversing that State to about $1,000,000
a year. The reduction in train lengths also impedes efficient operation.
More locomotives and more manpower are required; the necessary
conversion and reconversion of train lengths at terminals and the delay
caused by breaking up and remaking long trains upon entering and leaving
the state in order to comply with the law, delays the traffic and
diminishes its volume moved in a given time, especially when traffic is
heavy.

"At present the seventy freight car laws are enforced only in Arizona
and Oklahoma, with a fourteen car passenger car limit in Arizona. The
record here shows that the enforcement of the Arizona statute results in
freight trains being broken up and reformed at the California border and
in New Mexico, some distance from the Arizona line. Frequently it is not
feasible to operate a newly assembled train from the New Mexico yard
nearest to Arizona, with the result that the Arizona limitation governs
the flow of traffic as far east as El Paso, Texas. For similar reasons
the Arizona law often controls the length of passenger trains all the
way from Los Angeles to El Paso.

"If one State may regulate train lengths, so may all the others, and
they need not prescribe the same maximum limitation. The practical
effect of such regulation is to control train operations beyond the
boundaries of the State exacting it because of the necessity of breaking
up and reassembling long trains at the nearest terminal points before
entering and after leaving the regulating State. The serious impediment
to the free flow of commerce by the local regulation of train lengths
and the practical necessity that such regulation, if any, must be
prescribed by a single body having a nation-wide authority are apparent.

"The trial court found that the Arizona law had no reasonable relation
to safety, and made train operation more dangerous. Examinat