Back in the 1950's there was a wave of fear and hysteria regarding "juvenile delinquents". People were truly afraid of teenagers, a fear that would be fueled by movies, television, juvenile crime, and the news media. Scary teenage ruffians in movies and tv shows were often armed with switchblades. Many teens on the street also carried switchblades.
Between movies and television, actual teenagers using switchblades in fights or to commit crimes, news media fanning the flames of fear and hysteria, and politicians looking to make headlines and show the public that they are tough on juvenile crime, it's not at all surprising that many anti-switchblade laws were passed throughout the country.
Many of those laws are still in place today, but thanks to the efforts of Kniferights.org, and some state governors who actually applied reason and common sense to the subject of switchblades, some states have repealed their prohibitions on switchblades.
I'm sure you're already familiar, but another telling, very interesting medium of the day: young adult literature. If you go back and read the books written for the entertainment of young teens, it was shocking how many were not-so-secretly designed to make sure kids stayed on the straight and narrow. I remember one example in particular where at the end of the book, the "bad" group of kids had been drinking alcohol and all got into a car wreck and died. And that was pretty much the end of the book.