The regulating agencies, in their turn, had to improvise, to try one scheme and then another, to back-track—in short, had to learn how to do a job that had never been done before. The success of this joint effort is evident in the statistics of wartime travel.
MOTOR-VEHICLE REGISTRATIONS AND TRAVEL DURING THE WAR PERIOD
During the 20-year period just preceding World War II motor-vehicle registrations and traffic increased steadily, except for a slight, temporary dip during the depression years. The increase from 1921 to 1941 was more than threefold for registrations and approximately sixfold for vehicle-miles of traffic. In figure 10 the trends in population, registrations, and vehicle-mileage from 1921 to 1948 are shown, with 1940 as the base year.
Decline of traffic
In 1941 highway traffic increased at an accelerated rate, because of the abnormal activity preceding our entry into the war. Almost im-
