It’s pretty hard to count up all the guns in the United States, especially given how varied different states’ licensing and registration policies are. A 2012 Congressional Research Service report estimated that there were 310 million civilian guns in 2009: 114 million handguns, 110 million rifles, and 86 million shotguns. The Small Arms Survey, which measures gun prevalence internationally, estimated that there were 270 million in 2007. The latter estimate suggests there were 88.8 guns for every 100 people in the US in 2007; there were about 307 million people in the US in 2009, which would mean the CRS estimated there were more guns than people in America.
What share of households own guns is a different question, and surveys differ a bit on whether gun ownership is declining. The Pew Research Center’s polling and the General Social Survey suggest it is, while Gallup’s data is more equivocal:
But whether 43 percent or 34 percent of the population owns guns, it still suggests that gun-owning households have, on average, more than one gun. Indeed, a study looking at 2004 survey data found that households with guns have a median of 3 guns, and an average of 6.6. The latter figure is skewed upward by the sheer number of guns the gun owners with the largest stockpiles have; 65 percent of America’s guns are in the hands of 20 percent of gun owners.