How was "A & P" influenced by the political events during the time period it was wrote?
I am not too sure that examining the political events of the day and discussing their influence on the story can actually yield fruitful results. What is much more important to realise is how society has changed and how it was at the time of the story. Today, we have slipped into an informality that would have been completely alien to Sammy and his contemporaries. For Sammy and his generation, standards of how we should act and what we should wear were rigid and unyielding. This conservative approach to dress was paralleled by a similar approach to values and norms. Conformity was something that was greatly prized, and the desire above all was to fit in and not be different. Consider the way that suburbs were built consisting of identical houses. If you rejected conformity, you risked being known as "bohemian."
The way in which the 1960s have become known as a decade of rebellion is partly thanks to the way in which children felt that their parents were imposing strict rules onto them. You might want to analyse the character of Sammy to help you understand how this is a major cultural influence on the story. He disdains the "sheep" and refers to housewives as "houseslaves," which shows his contempt for following the crowd and conformity. His decision to quit in this kind of world is one that will make the world "hard" for Sammy from this point onwards, as it would be for anybody who rejects conformity and tries to live their own life in opposition to the values that are championed by their society.