By the numbers: Guns in the U.S.

Number of privately owned firearms by civilians in the United States:
270,000,000
(compared to number of military firearms: 3,054,553
and law enforcement firearms: 897,400)

World Ranking: No. 1

Rate of private gun ownership in the United States:
88.82
firearms per 100 people

World Ranking: No. 1

In the United States, the right to private gun ownership is guaranteed by law.

Guns are regulated by the federal, state, and local authorities: The federal legislation guiding gun control is the 1968 Gun Control Act; each U.S. state and territory enacts its own gun law.

Manufacturing small arms, ammunition and their components requires a valid licence.

Regulation

• Civilians are not allowed to possess machine-guns, sawn-off shotguns and rifles, silencers, and armour-piercing ammunition without appropriate registration.
• Automatic assault weapons: prohibited without appropriate registration
• Semiautomatic assault weapons: permitted without a licence in some jurisdictions
• Handguns: permitted without a licence in some jurisdictions

• Regulated by state or local authorities according to weapon type
• 18 years to purchase shotguns and rifles
• 21 years to purchase all other firearms

• Sales at licensed gun dealers: Buyer of a firearm is required to pass official background checks before taking possession
• Private sales: no checks are required

• Private guns are prohibited in federal facilities
• Carrying a firearm in plain view in a public place with or without a permit is allowed in some jurisdictions and prohibited in others.

Source: GunPolicy.org