A&P, the Great Atlantic and Pacific Tea Company, is a real grocery store (and liquor) chain, founded in New York City in 1859. But why write a story about it?
Updike says that one day in 1961 he was, as usual, on the lookout for story ideas when he happened to drive past an A&P. He wondered why nobody had ever set a story in one. He combined this question with a personal experience he once had at a grocery store: yes, he ran into a bathing-suit-clad beauty. He was stunned by how different this was from seeing someone in a bathing suit at the beach. Updike says this "public nakedness" in a "commercial setting" was the beginning of his story (source).
Updike is known for this kind of thing – taking ordinary aspects of American life and showing us how they are actually extraordinary. He calls this technique "giving the mundane its beautiful due." (See "Writing Style" for more on this.) Updike transforms this seemingly ordinary locale, which most of us can relate to, into an intense battleground where the struggle for power and freedom plays out in the aisles. By calling the story "A&P," Updike emphasizes that this particular setting (the grocery store) holds an important place in American life – one that's worth observing and writing about.
How does Updike's description of the A&P compare with your local supermarket chain? Could this story have taken place there? What things, if any, would you have to change to make the story work? What would you have to wear in your store for somebody to actually make a comment?