On what memorable day in history does this story take place?

The story takes place on 22nd November, 1963, the day on which President John F. Kennedy was assassinated.
It seems that everyone in Elena's neighborhood, including her mom, is deeply shocked and saddened by this tragic event, but Elena has other things on her mind. That evening she's scheduled to go to Eugene's place to study. Elena's very excited at the prospect; it's all she can think about, even on a day of national mourning. She has a big crush on Eugene; they've been getting closer, and Elena sees their forthcoming study session as an opportunity to get closer still.
As it happens, Eugene's mom won't let Elena into the house. She doesn't say it in so many words but she's clearly prejudiced against Puerto Ricans like Elena. What had promised to be such a wonderful evening ends in humiliation and disappointment for Elena. She returns home with her tail between her legs, feeling incredibly sad, albeit for completely different reasons to everyone else in the neighborhood.