All Aboard! 20th Century American Trains All Aboard! 20th Century American Trains In August 1999, the United States Postal Service issued a set of 33¢ postage stamps entitled All Aboard! 20th Century American Trains to ""pay tribute to American industry and design, and specifically to the heritage of our railroads."" Artist Ted Rose created five watercolor images depicting the following celebrated American named passenger trains from the 1930s and 1940s: Descriptive text regarding each of the trains was listed on the gummed side of each stamp. At the same time, the USPS offered for sale a booklet of "20 U.S. Postal Service Ready-To-Mail Stamped Postal Cards"
20th century were developed in the 20th century. In the first part of the 20th century, measure theory, functional analysis, and topology were established, and significant developments were made in fields such as abstract algebra and probability. The development of set theory and formal logic led to Gödel's incompleteness theorems. Later in the 20th century, the development of computers led to the establishment of a theory of computation. Other computationally-intense results include the study of fractals and a proof of the four color theorem in 1976. One of the prominent traits of the 20th century was the dramatic growth of technology. Organized