Unlike definitives, commemorative stamps are printed in limited numbers to honor an event, person, or specific theme. Postmaster General John Wanamaker issued the nation's first commemorative stamps in 1893. The series of sixteen stamps illustrated the Columbus's discovery of America. They prepared the way for the rapid growth of commemorative issues in the twentieth century.
Like the Columbians, early commemorative stamps were issued in sets of a few stamps. In the late 1920s and throughout most of the twentieth century, individual stamps were issued to commemorate a topic. Commemorative sets or panes of multiple images have again become popular, especially with the development of self-adhesive stamps.