What word in paragraph 1 signals that the text is memoir?

The word in the first paragraph of chapter 1 of Warriors Don't Cry that signals that it is a memoir is "I." Up until that "I," the story could simply have been a historical account of happenings in the 1950s, when teenaged girls listened to Buddy Holly and watched Elvis. The "I" changes everything.
A memoir, as the name indicates, is a personal account of a historical event as remembered and experienced by a particular individual. It does not aim for objectivity; it is a subjective account of how a significant event or time period felt to or affected one person. It differs from an autobiography because it does not attempt to take the reader through an entire account of someone's life: its focus is on a specific period in that person's life.
Memoirs, though they have to be verified by more objective sources, are very valuable to historians because they are first-person or eyewitness accounts of events. People who lived through an experience have a perspective on it that is hard to replicate. Memoirs add color to the dry facts of history.
Beals's account of being one of the first nine black students to integrate into Little Rock high school offers the kind of detail and personal perspective that make that historical event come alive and seem real.