Robert Hartmann operates a reconstructed version of Johann Gutenberg’s printing press in the Gutenberg Museum in Mainz, Germany. The first printing presses are made in America in 1769. By the Revolutionary War, printing presses were publishing dozens of weekly newspapers and pamphlets such as Thomas Paine’s Common Sense, which encouraged the revolt against the British. In 1776, more than 20 newspapers published the full text of the Declaration of Independence. (© AP/WWP)