"During the early 20th century these fireworks became bigger, more powerful, and dangerous. Between 1900 and 1930 more than 4,000 people were killed by fireworks. Governments began regulating the use of fireworks in the 1930s. Explosives are classified as Class A , Class B and Class C. Class C fireworks must not contain more than 50 mg of explosive. Some very dangerous fireworks, such as cherry bombs, M-80s, and silver salutes, are banned in all states, but continue to be made and sold illegally. Most firework deaths and injuries in the United States today are caused by these illegal devices."