Sitcoms in the 1950's were, by today's standard, very stereotypical. There was no focus on minorities or family issues that were taboo at the time. They portrayed normal white middle-class families with a houswife, two children, and a hard working father. Think of Leave It To Beaver or I Love Lucy type shows.
Adding onto SPARTANMAFIA’s answer they believed in manifest destiny where they thought they should have all of North America and that’s the way it should be
