In the United States, the first comic book was published in 1934. Ever since the first comic came out, the leading producer has been the United States. The first comics were similar to the comics found in early newspapers; however, they were published as their own books. The first comic books were mostly about adventure stories and depicted some type of superhero character. Historians break up the history of American comic books into different eras. There are four eras starting with the Golden Age, the Silver Age, the Bronze Age, and the Modern age of comic books. The Golden Age of comics is said to have last from the 1930s to the late 1940s. During this time, comics became main stream and readers were introduced to superheroes such as Batman, Captain America, and Wonder Woman. Superman was the first known superhero and made his debut in 1938. After Superman, almost all comics featured a superhero, and the Golden Age is classified by their appearances. World War II had a big impact on the popularity of the superhero comic books during this era. What made them so popular was showcasing that good triumphs over evil. There were even some comic books that showed characters punching Adolf Hitler. The Silver Age of comics was more about commercial success and artistic advancement. The Golden Age proved that comics were popular and readable, and the Silver Age maintained that success. This ere lasted from the mid 1950s to the early 1970s. During this time, comics were blamed for juvenile crimes occurring more frequently. As a result of this, comic sales went down and writers had to rethink their story plot. Comics started to represent authority. The characters went through a dynamic change and the stars of the comics started to appear as aliens and other science fiction characters. Also during this time, underground comics made for adults started to emerge. The Bronze Age lasted from the 1970s to the mid 1980s. The look of the comic book didn't change during this era, however, the story plot changed dramatically. Although the pages and pictures were bright and colorful, the story line was more dramatic, realistic, and dark. Real world issues were brought to attention in the comics of this era. Drug use was an issue addressed. The comics became more mature and life like. The Modern Age of comic books started in the 1980s and continues on in to the present. In addition to the characters in comics, the writers are also more recognizable. There are more publishing houses that produce comics and there are independent comic books too. The larger publishing houses became more commercialized. The characters also change during this era. They are now more complex, show self doubt, and the villains are darker.