No, they haven't. From 1847 to 1922, most of America's stamps were produced on flat bed presses. Printing stamps this way was a slow process, because the presses could print only one sheet of stamps at a time. In 1923, the Post Office Department decided to use rotary presses to print regular issue stamps because these presses were faster and could keep up with the increasing demand for stamps. Rotary presses improved printing efficiency because they could print sheets of stamps on a continuous roll of paper. Stamps produced on a rotary press are longer or wider than the same stamps printed on a flat bed press. Today, many stamps are printed by offset. This is a printing process in which an inked impression from a plate is first made on a rubber-covered cylinder and then transferred to the paper being printed. Offset printing is less expensive and more flexible for the production of multicolored stamps.