In the United States, the minimum legal barrel length of a shotgun is 18 inches. Shotguns with shorter barrels must be federally registered and are subject to taxation.
These legal restrictions have been in place since the 1930s, in response to gangster gun violence. Short-barrel shotguns are attractive to criminals because they are easily concealed, powerful at short range and leave fewer forensic details for investigators to identify. This attractiveness led to them being targeted by the federal government in the National Firearms Act. The National Firearms Act also covers rifles and levies a 200 dollar tax on owning one. Individual states may put further restrictions on shotgun ownership, regardless of length.