Ryan Murphy has already said Freak Show is going to be a 1950's period piece. Here's some things that happened in the 1950's that might be involved.
First organ transplant, Korean War, Vietnam War, Red Scare, Communism, Hydrogen Bomb, nuclear weapons, atomic submarine, first TVs, Polio Vaccine, Racism in general (segregation, Emmett Till, Rosa Parks), Sputnik, NASA founded, Rosewell (Sci-fi??), Elvis Presley, Rock n'Roll.
Jessica Lange has already been said to have been working on an accent. Any thoughts on what could happen?