And that assumption would be dead wrong.... I believe its something like 1/4 or so.
Per person or per Family? If its per person then i am right.
Falls down laughing. Oh man. No, not everyone in America has a gun. In fact a higher percentage of Canadians own firearms than do Americans if I'm not mistaken.
However in the 1940s I would imagine 1/4 or perhaps 1/3 homes had a usable firearm in it. Rural areas naturally increase this ratio. But by this time the prohibition crime era was over so the need for having a gun in an urban or suburban environment was less present.
PS
90 guns per 100 people means nothing. People in the US like hording guns. So if a person owns one gun, they probably own at least one or two more, like Warrior said.