21¢ Chester Carlson
Great Americans Series
Issue Date: October 21, 1988
City: Rochester, NY
Printed By: Bureau of Engraving and Printing
Printing Method: Engraved
Color: Blue violet
While working at a New York electronics company's patent office, Chester Carlson saw a need for making quick, inexpensive reproductions of documents and drawings. Using his knowledge of chemistry and physics, he developed xerography - the process of using electrostatic action to transfer dry powder on copy paper. In 1948, the Haloid Company of Rochester, New York, introduced the first Xerox copier. Carlson is pictured on the 21¢ Great Americans stamp.
Issued between 1980 and 1999, the Great Americans definitive series features 63 designs, making it the largest set of face different Regular Issue stamps issued in the 20th century. One stamp honors a couple (Lila and Dewitt Wallace) while the remaining 62 commemorate individuals.
The series is characterized by a standard definitive size, simple design and monochromatic colors. The Bureau of Engraving and Printing produced most of the stamps, but some were printed by private firms. Several stamps saw multiple printings. The result is many different varieties, with tagging being the key to understanding them.