During america's first two centuries, the national character was marked by individualism. why do you think conformity became the norm in the 1950s?

Communism and fear--Following WWII, the US had a new enemy and trusted the government to protect them from the USSR. They did this by following the rules of the government. 

Communism threatened American values of capitalism and democracy as well as Christianity. The US promised to keep Americans safe from nuclear war but the had to do it as a unit or nation. This required people to follow instructions and conform to American ideals. Those that did not conform were named as Communists, Reds, or even Pinkos (Communist sympathizers) all of which were seen as the enemy.