This stamp depicting an automobile marks the beginning of a new series of U.S. stamps: American Transportation. Non-denominated with a face value of 10 cents, the stamp was issued for use on regular third-class bulk mail. Automobiles are a major part of American life. During World War II the motor vehicle industry was the largest single factor in the nation's total manufacturing resources. The industry produced $29 billion worth of military materials, one-fifth of the total American output.